A workaround for users still having issues with the calendar. There was a problem with the node-ical package for some events. This has just been fixed with a new node-ical release (v0.26.0).
To use the new version, run this command in the MagicMirror directory:
npm install node-ical@latest.
Note that this will change your package.json and package-lock.json files, which would cause conflicts during the next MagicMirror update. Therefore, also run the following to restore them:
git restore package*.json
You will then have v0.26.0 installed - the package.json file say otherwise, but that doesn’t matter.
Please give some feedback if that helps :-)