ok, i found the “mismapped Note” vs my SL Grand in that other rack, and removed it.
this does NOT solve the problem in my problem rack.
But there is NO such note from my SL Grand mapped in that problem rack.
i have no entry in the midi assignements vs. my SL Grand vs. the failing Rack.
no such note mapped in global midi.
i understand this aspect, ie. global midi and waht i have set there
a restart of the computer has solved this issue now.
to notes:
i had deinstalled the PA GP, and installed the deskew GP this afternoon, and much likely have NOT powercycled the mac
edit:
from “midi assignement” window:
there is no possibility to delete a mapping, or even the whole widget, right ?
—> will turn into a feature request, in case i missed something
Yes, it just gives you an overview.
You cannot delete or map something inside that window.
That’s not true, it lies in the current rackspace and global rackspace only.
“i interpreted” 
one of your sentences vs. my latest problem this way.
Ok, thats no corrected. I have the picture right again.
But this means that something very strange happened !
since the problem rackspace had NO, not one midi mapping vs. my SL Grand present.
There was just none.
finally was it the restart of the computer that solved the problem…
so, Problem solved (again) !
but some “mystery” / non-understanding vs. what happens, remains.
Thanks again everybody !!
Indeed - not sure why rebooting would change anything unless you had assigned something by mistake and rebooted without saving the gig file
possible that i did not saved bevore the reboot.
But: its very unlikely that the cause of failure was not part of my saved version.
i´d guess i reloaded the gig, probably even more than once, bevore coming here.
fact is: i save quasi after any change i make / ie. widget/mapping development, or developing the patch itself. i PERMANENTLY do a quick save ! mac: [command +S]
old habit from dealing with flaky grooveboxes in beta state ( elektron)
Its the advantage of how my mac qwrty and TP is placed, how flush and quick this goes !
while: the whole initial cause of “my” Fail vs. the problem of this topic/thread,
IS also based on that setup arrangement. ( prone to press a key down unwantedly, while mapping widgets)
Elektron grooveboxes are the fastest ones vs. doing a quick save !
but fact is: on my setup vs. GP…i´m even faster than with a elektron 