In Custom Space User Management Plugin a user can't be removed from a space group

[Stefan Baader]

We are running CONF 5.5.2 and are using the Add-On "Custom Space User Management Plugin". A space owner is complaining that he is not able to remove one of the users from one of his space groups. I checked that and he's right. The click on remove end in a confirmation that the user has been removed. But he is still shown in the list. When I check the user and his groups in the Admin area I see that he is indeed removed from that group.
I tried then to add more users and remove them again using the plugin. It was successful. That special user is also not disabled or has other criteria.I created a new space group with the plugin and added that user and removed him. Also successfully.

But in that one group it is not possible to remove that one user.

I flushed the cashes and rebuilt the index.
What could be the reason for that?

[Gary Weaver]

Let's discuss here: https://github.com/sillycat/confluence-space-user-management/issues/24

Thanks!

[Gary Weaver]

I don't think this is related. Will put more in answer below.

[Stefan Baader]

We still have that issue. I recognized the following old issue https://jira.atlassian.com/browse/CONF-9035 cloded with "won't fix". Any idea from anybody?