Same issue with ff 68 esr - due to company restrictions. Calendar with nc20 works fine on my private system running ff 84. Hoping for a fix, because I don’t expect our company admins will upgrade ff to an actual version (ff 68 esr has been issued in august 2020) soon. On december 15, 2020 ff has published ff 78.6 esr, hopefully calendar works with that version.
After the Update from 20.0.4 to 20.0.5 I see the headline and the left side but the calendar grid is missing.
I think this is only partly fixed whereas the github issue is closed.
I will uncheck the solution cause it is still not working