I have been experiencing this same issue for the past few days: material thumbs in the tool box are visible on the main display, but if I move the materials tool box over to the extended area of a second display, the thumbs are gone.
I use both SU8 and SU2014 (the latter more often recently), Windows 7. Main display is on an Acer laptop which I’ve been using for a couple years. Extended display is a 22" Acer monitor. I have had that monitor for several years, and have been using it for extended display for about two years. Resolutions on the two displays are not the same and never have been - I set each so that perspective is not distorted when I am drawing, and that everything will be displayed the same no matter which display I drag something to. I have never had the problem of material thumbs not showing until a few days ago. And while I normally have my tool boxes on the laptop display and the SU screen on the larger extended display, I often move the material tool box back and forth across the two when needed, and have never had this problem. I’ve installed no new programs, added no new peripherals… nothing about my environment has changed other than Windows updates for Windows and Microsoft products.
Don’t know if the following will be of any help to anyone, but here are three other things I’ve noticed since this issue began a few days ago:
1. I have my tool box sized in such a way that there are five thumbs on each row, and three rows visible. In SU8 it is only the first row of thumbs (five thumbs) that displays no materials. In SU2014, it is the first and second rows of thumbs (ten thumbs) that display no materials.
2. If I click on any of the thumbs MIA, they do appear in the preview window and their name appears in the information box - but still not in the respective thumb box
3. If I scroll down thru the material thumbs, the various materials are visible as I scroll down, but when I scroll back toward the top, the thumbs become blank and remain that way until I close or minimize the tool box, or minimize SU, after which, when I reopen/restore, the view returns to what I described in #1 above.
I’m not so sure I understand what @MikeWayzovski has suggested be done to alleviate the problem (looks to be way over my head)… but wanted to at least offer to the OP that he’s not the only one with this issue that has cropped up suddenly. It’s just beyond me why it happens on an extended display but not on a native one.
Good luck, @GTh