You are unfortunately not alone in experiencing these kinds of annoying glotches in Rig Manager. I have had many many such issues recently including slots within performances being mixed up and unable to be be changed back into the right order no matter what I do.
Basically the current RM is pretty rubbish and full of bugs. Fortunately, Kemper have a wonderful new Rig Manager/Editor in internal testing and due for release this summer. As we are now in Summer time I for one am hoping to see it very soon ?
It looks like it is going to be AMAZING ?
Glad to hear I am not alone, and definitely looking forward to a new (stable) editor! It seems every other time I plug my KPA into my RM I get the USB error