There are some troubles with the Group folders again:
Please be aware of GF 4.1.3 trouble with advanced permissons #635 and related issues.
This issue is currently WIP and under investigation. My sincere apologies if early assumptions were misleading.
[RESOLVED] Issue B:
Please be aware of
Sync with desktop client not working with GF 4.1.0 and Nextcloud 16.0.4 #597 Desktop client not syncing changes #597.