Calendar: How to undo "unshare from me"

Nextcloud version (eg, 20.0.5): 20.0.8
Operating system and version (eg, Ubuntu 20.04): unknown
Apache or nginx version (eg, Apache 2.4.25): unknown
PHP version (eg, 7.4): unknown

The issue you are facing:

I clicked “unshare from me” on a shared calendar and now I want it back.
How do I restore access to this calendar?

What we have tried:

  • The user who owns the calendar tried un-sharing it to the group I’m a part of and then re-sharing it to this group again.
  • I have been removed and re-added to the group that the calendar is shared with.
  • The calendar has been shared with me directly and this results in me having access to the calendar again but this is not a long term solution because the owner of the calendar is a shared system-user account which future admins using this account will see that I am a member of the group and so may remove the direct share as general housekeeping.

I assume there must be someone where in the database that lists me as having “Unshared from me” this calendar and I again assume that this could be manually reset. Can anyone tell me if this is true and/or whether doing so is likely to cause other errors?