I don't know if anyone can help me, but on my server we're using group manager as a permission and prefix plugin. We had a player change their username and now their rank has disappeared and they can't get it back. Funny thing is, when I do /manuadd -username- -rank- they have all the permissions except for the prefix. This has happened to a few people including myself, but I can't seem to find the main problem as to why this is actually doing that.
Please do not suggest using PEX only because I've had problems with PEX before, and have no desire to use that plugin.