Birthdays created in Android show up in NC web iface, but don't show up in Thunderbird Calendar

Hello, I use Nextcloud 22.2.3 from a snap. Calendar app is 3.0.5.

My Android is version 12. Davx5 is the latest version, 4.1-ose.

My Thunderbird is latest version, 91.5.1. BTW: My Cardbook Extension is the latest version, 73.7, which works great for contacts, and Birthdays created in Android are shown there (in the Cardbook tab), in their respective column. Just not over in Thunderbird’s Calendar.

I can display Calendar events over in Thunderbird Calendar, if originally made in Android (then synced via Davx5 → NC → Thunderbird Calendar). But if Birthdays are made in Android, then similarly synced through Nextcloud? The Birthdays will show in Nextcloud through the web interface, but then syncing from Thunderbird Calendar won’t show Birthdays (this is after a successful connection; URL, username and password for Nextcloud was accepted, when adding “Contact Birthdays” calendar, using the URL provided in Nextcloud Calendar → Contact Birthdays → Copy Private Link).

It’s possible that this issue is related to this other thread:

BTW: I’m using Ubuntu 20.04 on my laptop, and the Gnome Calendar app does work, to show birthdays from Nextcloud.