The problem with not updating looks like it’s related to one of my calendars not having any entries in the requested timescale. If all calendars have entries then they sync however if one (in my case the last one) has no entries then there are no updates. Very strange.

Thanks for the detailed description, I’ve done this and it works most of the time, however one of my calendars is not updating.
I know very little about Pi’s and am new to Linux it general, are there any suggestions on how to find issues?