There is an issue with iCloud sync when the sync folder is changed from '/org' to '/' or ''. As a workaround change back to syncing to a folder such as '/org' within the beorg iCloud folder.
I don't think this is an iOS 14 issue as such but likely the update to beorg 3.7.1 which introduced this bug.
Let me know if the above workaround doesn't fix your issue. I hope to have a fix out ASAP.
Thanks for your patience with this. I'm hoping to release an update in the next couple of days which fixes both the issue you experienced and the share extension - just doing some final testing now before submitting to Apple.