Hello, since the Nextcloud 34.0.1 update, a bug has been observed. If you try to add a group to a user, all groups previously associated with that user disappear (you would then have to re-enter all the old groups in addition to the new one).
Thank you in advance for fixing this.
Workaround found: you have to go to a group where the user already exists. You can see all the groups they belong to and add another one. But it’s not exactly elegant; plus, you have to juggle searches—first for the user to find a group they belong to, then for the group itself to access it.
Bug reports need to go to GitHub: GitHub - nextcloud/server: ☁️ Nextcloud server, a safe home for all your data · GitHub
Might get noticed here, but the forum is more a technical support channel.