Muting notes inside the midi editor sometimes
renders Cubase GUI unresponsive (toolbar or any other clickable item) for several seconds and the cross mute cursor gets changed to an arrow.
it also scrambles the display of notes which disappear altogether, you can’t even visually recognize the MIDI sequence you were editing
The Macro menu appears filled (it’s large, up and down arrows enables you to scroll it) with emptiness: it’s a white box with nothing inside
…
Without knowing anything about your DAW configuration it is going to be difficult for anyone to offer more than generic suggestions. That’s one of the reasons we encourage folks to include their system specs in their signatures so we don’t have to ask (hint, hint). 
When it scrambles the notes is it just not displaying them correctly or do they play back scrambled too?
Thanks for caring Raino. I was writing, not playing back, so I don’t know. I use the past tense cause I’m back on C10 Pro until some fixes show up. I didn’t list my DAW cause I didn’t want Seven to provide an excuse for C10 basic stable features becoming unstable in C10.5
I’m trying to understand if when this scrambling occurs is it changing the MIDI Data itself, or perhaps it is just a problem with the graphic display.
It’s hard to visualize what is occurring based on a text description. Before & after screen shots could be useful.