XF 1.5 Thread prefixes --> Forums and permissions (will not save)

[raytrails]

I have set up a Thread Prefix Group with 1 prefix. But in Forums and permissions, when I have selected the one usergroup which will have the permission to use it, it refuses to "stick" after saving. Next time I check the prefixes available for that specific forum, all of them are checked. And it doesn't help deselecting every group but the one, and saving it. Next time I go into Forums and permissions, every usergroup are selected again. I have selected the "Selected User Groups:" and not all usergroups.

What am I missing here?

 

[Mike]

I guess the primary thing to check would be add-ons. If none of them are causing it, I suppose it could be something like Suhosin? (We have seen some odd behaviors from that in the past.)

If that doesn't show anything up, would you mind adding some screenshots to confirm what you're editing specifically, in case we're talking across locations here?