Sorry to bring up an old thread, but I ended up getting to busy to finish dealing with that issue back when I started the thread. I think I ended up just creating an individual event for each item on the calendar if memory serves.
I have run into the issue again though. I went through the responses of the person with the same issue, and was about to try and add in those same fixes however it appears that they are part of the main program now.

I pulled the ICS file, and the debug file from the event and will attach them here, but from my very basic understanding, it almost appears that it is changing the time zone on the recurring event even when that isn’t appropriate, I am assuming that is where the issue is arising from.

ics:

BEGIN:VEVENT
DTSTART;TZID=America/Edmonton:20220510T190000
DTEND;TZID=America/Edmonton:20220510T210000
RRULE:FREQ=WEEKLY;UNTIL=20220713T055959Z
DTSTAMP:20220504T175603Z
UID:E273826A-0F74-4F0D-BA17-A59824B3D8AC
CREATED:20220216T184435Z
DESCRIPTION:
LAST-MODIFIED:20220216T184435Z
LOCATION:xx
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:Class
TRANSP:OPAQUE
END:VEVENT

Debug:

{"type":"VEVENT","params":[],"start":"2022-05-11T01:00:00.000Z","datetype":"date-time","end":"2022-05-11T03:00:00.000Z","rrule":{"_cache":{"all":false,"before":[],"after":[],"between":[]},"origOptions":{"tzid":"America/Edmonton","dtstart":"2022-05-11T01:00:00.000Z","freq":2,"until":"2022-07-13T05:59:59.000Z"},"options":{"freq":2,"dtstart":"2022-05-11T01:00:00.000Z","interval":1,"wkst":0,"count":null,"until":"2022-07-13T05:59:59.000Z","tzid":"America/Edmonton","bysetpos":null,"bymonth":null,"bymonthday":[],"bynmonthday":[],"byyearday":null,"byweekno":null,"byweekday":[2],"bynweekday":null,"byhour":[1],"byminute":[0],"bysecond":[0],"byeaster":null}},"dtstamp":"2022-05-01T23:21:41.000Z","uid":"E273826A-0F74-4F0D-BA17-A59824B3D8AC","created":"2022-02-16T18:44:35.000Z","description":"","lastmodified":"2022-02-16T18:44:35.000Z","location":"Canada","sequence":"0","status":"CONFIRMED","summary":"Class","transparency":"OPAQUE","method":"PUBLISH"}
[01.05.2022 17:21.45.608] [DEBUG] start: Tue May 10 2022 19:00:00 GMT-0600 (Mountain Daylight Time)
[01.05.2022 17:21.45.610] [DEBUG] end:: Tue May 10 2022 21:00:00 GMT-0600 (Mountain Daylight Time)
[01.05.2022 17:21.45.629] [DEBUG] duration: 7200000
[01.05.2022 17:21.45.633] [DEBUG] title: Class
[01.05.2022 17:21.45.637] [DEBUG] Search for recurring events between: Sun May 01 2022 17:21:45 GMT-0600 (Mountain Daylight Time) and Wed Jun 29 2022 23:59:59 GMT-0600 (Mountain Daylight Time)
[01.05.2022 17:21.45.654] [DEBUG] Title: Class, with dates: ["2022-05-11T01:00:00.000Z","2022-05-18T01:00:00.000Z","2022-05-25T01:00:00.000Z","2022-06-01T01:00:00.000Z","2022-06-08T01:00:00.000Z","2022-06-15T01:00:00.000Z","2022-06-22T01:00:00.000Z","2022-06-29T01:00:00.000Z"]
[01.05.2022 17:21.45.656] [DEBUG] event.recurrences: undefined
[01.05.2022 17:21.45.659] [DEBUG]  recurring date is Tue May 10 2022 19:00:00 GMT-0600 (Mountain Daylight Time) offset is 360
[01.05.2022 17:21.45.663] [DEBUG]  recurring date is Tue May 10 2022 19:00:00 GMT-0600 (Mountain Daylight Time) offset is 6 Hour is 19
[01.05.2022 17:21.45.665] [DEBUG] new recurring date2 is Wed May 11 2022 19:00:00 GMT-0600 (Mountain Daylight Time)
[01.05.2022 17:21.45.666] [DEBUG] Corrected startDate: Wed May 11 2022 19:00:00 GMT-0600 (Mountain Daylight Time)
[01.05.2022 17:21.45.666] [DEBUG] initial tz=America/Edmonton
[01.05.2022 17:21.45.667] [DEBUG] corrected tz=America/Edmonton
[01.05.2022 17:21.45.668] [DEBUG] start date/time=Tue May 10 2022 19:00:00 GMT-0600 (Mountain Daylight Time)
[01.05.2022 17:21.45.669] [DEBUG] start offset=-360
[01.05.2022 17:21.45.672] [DEBUG] start date/time w tz =Tue May 10 2022 19:00:00 GMT-0600 (Mountain Daylight Time)
[01.05.2022 17:21.45.674] [DEBUG] event date=Wed May 11 2022 19:00:00 GMT-0600 (Mountain Daylight Time)
[01.05.2022 17:21.45.675] [DEBUG] event offset=-360 hour=19 event date=Wed May 11 2022 19:00:00 GMT-0600 (Mountain Daylight Time)
[01.05.2022 17:21.45.676] [DEBUG] adjustHours=0
[01.05.2022 17:21.45.676] [DEBUG] duration: 7200000
[01.05.2022 17:21.45.678] [DEBUG] saving event: false
[01.05.2022 17:21.45.680] [DEBUG]  recurring date is Tue May 17 2022 19:00:00 GMT-0600 (Mountain Daylight Time) offset is 360
[01.05.2022 17:21.45.681] [DEBUG]  recurring date is Tue May 17 2022 19:00:00 GMT-0600 (Mountain Daylight Time) offset is 6 Hour is 19
[01.05.2022 17:21.45.683] [DEBUG] new recurring date2 is Wed May 18 2022 19:00:00 GMT-0600 (Mountain Daylight Time)
[01.05.2022 17:21.45.684] [DEBUG] Corrected startDate: Wed May 18 2022 19:00:00 GMT-0600 (Mountain Daylight Time)
[01.05.2022 17:21.45.685] [DEBUG] initial tz=America/Edmonton
[01.05.2022 17:21.45.688] [DEBUG] corrected tz=America/Edmonton
[01.05.2022 17:21.45.694] [DEBUG] start date/time=Tue May 10 2022 19:00:00 GMT-0600 (Mountain Daylight Time)
[01.05.2022 17:21.45.696] [DEBUG] start offset=-360
[01.05.2022 17:21.45.697] [DEBUG] start date/time w tz =Tue May 10 2022 19:00:00 GMT-0600 (Mountain Daylight Time)
[01.05.2022 17:21.45.698] [DEBUG] event date=Wed May 18 2022 19:00:00 GMT-0600 (Mountain Daylight Time)
[01.05.2022 17:21.45.699] [DEBUG] event offset=-360 hour=19 event date=Wed May 18 2022 19:00:00 GMT-0600 (Mountain Daylight Time)
[01.05.2022 17:21.45.700] [DEBUG] adjustHours=0
[01.05.2022 17:21.45.700] [DEBUG] duration: 7200000
[01.05.2022 17:21.45.702] [DEBUG] saving event: false

@sdetweil okay, I went through and changed my original calendar to make sure all events were in the correct time zone, but I was able to make a test event that was the same as the example. If I am understanding correctly, you want me to add // immediately in front of the “if (event.start…” as well as the second set of brackets at the end, two lines down from the “Log.debug…” line, around about lines 348 and 376?

I did try this, both with the system time zone in Edmonton, and Vancouver. Both resulted in the event still displaying on the 22nd.
I may have misunderstood what you were asking though as I am very new to this, and have no previous experience with javascript, aside from what I have been able to learn in the last few weeks setting this up.

One other aside, I have also noticed that all day events are being displayed correctly ahead of time, as well as day of- however the day after the event is scheduled it will remain, and display as an event scheduled that day. (example event will show in 2 days, 2 days ahead of time, ends in x hours on day of, but also shows ends in x hours 1 day after event was scheduled). Is this related to the same type of timezone issues as the original?

@sdetweil This event shows on the 22nd at 6pm rather than the 23rd. I do notice that for some reason the event shows as Vancouver time zone rather than Edmonton, perhaps that could be affecting something (even though it should only be 1 hour different…)

BEGIN:VEVENT
DTSTART;TZID=America/Vancouver:20201126T170000
DTEND;TZID=America/Vancouver:20201126T180000
RRULE:FREQ=MONTHLY;WKST=SU;BYMONTHDAY=23
DTSTAMP:20211118T181948Z
UID:55A45619-xxxxx-4425-xxxx-1EFBAFDC2DE0
CREATED:20201119T060211Z
DESCRIPTION:
LAST-MODIFIED:20201119T060211Z
LOCATION:
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:Test
TRANSP:OPAQUE
END:VEVENT

@sdetweil both the Calendar, and my Magic mirror are on the Mountain/Edmonton time zone.

I have noticed that some events (particularly those later in the day, or all day events) have been showing up a day late. I have tried adjusting the config options to absolute on the calendar module, as well as updating to the most recent develop version, however neither of these have fixed the issue. Has anyone else had run into this issue, or know how to fix it?