Now on Lightning 68.7.0, same problem Every time I open TBird, the Lightning Calendar appears as pictured in the attachment. No new entries can be entered and there are no updates. Following other's suggestions, resetting "extensions.installedDistroAddon.{...}" in advanced config, then removing the Lighting add-on sometimes works but many times does not.

This is extremely frustrating and wastes lots of time! Is anyone looking into this? Thank you

So is your issue the provider or the calendar? as the provider is an addon that is not provided as a part of Thunderbird support for it is provided by the author. https://addons.thunderbird.net/en-US/thunderbird/addon/provider-for-google-calendar/?src=ss

Provider brings in the Google Calendar data. The existing Google Calendar events do appear (as pictured above), so I'm thinking that the problem is with the calendar itself.

I've tried disabling Provider, restarting, enabling, restarting. That sometimes corrects the problem, but so does removing Lightning and resetting 'extensions.installedDistroAddon.{e2fda1a4-762b-4020-b5ad-a41df1933103}' in the config editor, and then having Lightning reinstall itself.

Either fix requires 3-4 attempts to work. Any time Thunderbird is restarted, it happens again.

Thanks

I suggest you try adding the calendar again as caldav. This will loose tasks, but it will make it a little easier to determine where the pint of failure might be.