@GTh -
On the seperate thread I started re: this same issue, @RLGL suggested repairing the MS VC ++ Red, which I tried w/o any luck. But @catamountain suggested doing a system restore - which I decided to try since it appeared this was something you had not. I had not yet uninstalled any of the MS VC ++ Red’s.
I had to restore all the way back to 04 Aug - I had not to that point uninstalled/re-installed either of the versions of SU that I use. Believe it or not, when I slide the materials toolbox over to the 2nd monitor… all the materials thumbnails were present and accounted for. So for now… all is well.
I do, however, wonder what will happen when the MS VC ++ Red 2015 vs 14.~ is updated again …