Occasionally I have the same strange behaviour.
But I cannot reproduce it.
Sometimes restarting the RM helps.
Maybe RM and Toaster are loosing snchronity ?
Happened again.
Rig Manager open, some fonding around with Green Scream in Slot B, Store - Replace.
Switch to next rig at Kemper, suddenly the treated rig was doubled and the rig I switched to is gone.
Correction : Not doubled rig.
The rig to be replaced was NOT replaced. Instead of the next rig in the list was overwritten.
no CAPS LOCK please
I never found renaming and saving rigs a one step process. After you rename a rig, don't just hit the ENTER key. Click off and on a stomp, stack, or effect and then click the "Store Rig" button. That works for me.
Very strange ... I figured out :
For saving I use always the Store-Button of the real Kemper.
In addtion I ensure that in RigManager the focussed and selected rig is unchanged.
And after storing I wait at least 10 seconds before touching anything except a cup of coffee.
Didn´t have any problems since updating toaster to 8.7.8 
Using for hours without thinking about anything.
Kock on wood !
Wood was not good enough - one my favourite rigs disappeared yesterday. 
