The case sensitivity was my issue too! I think I pulled the github down *Wunderground* it installed with the folder name in lowercase, but the files themselves *WunderGround* and I was using MMM-Wunderground in my config.
Once I symlinked the correct capitalization, and corrected my config, it works perfectly.

20 years using linux, one would think I would catch this myself!

Thanks for asking the right questions! This thread got me up and running.

@Chadeus Replying to myself, but wanted this for the community.

It was about fixing the rrule-alt file and I changed it from 1970 to 1900 per the above link. Specifically: /home/pi/MagicMirror/node_modules/rrule-alt/lib/rrule.js

Change: ORDINAL_BASE: new Date(1900, 0, 1), /* changed from 1970 to 1900 */

Also, I generated a fresh private url for my Google Calendar. Not sure if that plays into it or not, but it worked after the changes plus getting a new url.

I used most of this information and I can’t thank everyone enough for all the contributions. Thank you.