User Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:69.0) Gecko/20100101 Firefox/69.0

Steps to reproduce:

TB 68.1, Lightning up to date. Fresh new install on a new computer (W10 64bits).
I created custom color categories for my Lightning calendar.

Actual results:

When editing a given event imported from Google Calendar via the "Provider for GC" addon, I can select the category in the drop-down menu, but the colors don't show in this menu and nothing changes in the calendar general view (weekly mode). I tried deleting my categories in the options menu and creating new ones; no change. The calendar is not in read-only mode as I can edit everything else except colors.
Help! Thx

Please not the exact Lightning version as listed in Help > Troubleshooting Information > Extensions.
Please ensure that category names do not contain spaces due to bug 1578982.

Does it work when using Lightnings built-in local calendars? If the problem is only observed when using Provider for Google Calendar you might want to report it here: https://github.com/kewisch/gdata-provider/issues

Hi. Thanks for the reply.
Thunderbird V. 68.1
Lightning version is 68.0.
GC Provider is 68.0 as well.
No other addon installed.

My categories are 1 word without space. I created 4 generic categories for the purpose of the test.
When using the built-in calendar locally:

• Selecting color #1 in my list results in the appearance of a generic small vertical colored bar on the right handside of the event, but the bar is the default color of the calendar and not the color of the category I chose.
• Selecting any other color in my list results in the event being the right color in full, but the name of the event disappears, as if the color is above the text with no transparency.
• This is also true for shared Google Calendar events: If someone creates an event on their calendar and associates it with me, the event shows on Lightning all right, with the right color in full, but some level of transparency so I can see the name of the event. As soon as I accept the event by confirming I'll attend, transparency vanishes and I can no longer see the name of the event (however, the color remains and is the right color).

Besides, when selecting the categories in the edition popup, the names of the categories show in the drop down list, but not the corresponding colors. Is this normal on this version ?

I know this is a lot. I'm thinking full re-install with an older version of TB to see if this solves anything. Thanks for your help.

The issue regarding category color filling the entire event ought to be fixed with Lightning 68.1 but you are still using Lightning 68.0.
Try reinstalling Thunderbird 68.1 to see if this installs Lightning 68.1 too. If it is still 68.0 uninstall Lightning and force installation of the bundled 68.1 by resetting the preference as described in https://support.mozilla.org/en-US/kb/calendar-updates-issues-thunderbird#w_when-i-use-my-user-profile-from-a-previous-thunderbird-version-with-a-newer-version-of-thunderbird-lightning-is-not-updated

Perfect. I'll do just that.
Considering the awkward behavior, a full re-install seemed appropriate anyway.
When checking add-ons, TB tells me some updates exist, but when trying to scan for automatic updates, it says everything is up to date so I reckon a forced installation of the package should solve the issue. I'll unsintall everything and will start fresh again.
Thanks for your help. I'll keep you posted and will close the bug report if it's fixed.
Cheers.

Hi again,
problem solved thanks to your link. I had to manually wipe any remains of TB in AppData in order to make it work but things are back on track after a couple of reinstalls.
Thank you so much for your help.