Not sure if this is a known issue, as I've tried and failed to find anyone else with it, but certain games in my library have started to just show blank tiles in the column on the left of the app. The tiles load and show up after I click on the game, but the next time I load Galaxy they are gone again while the rest remain. Always the same games every time...

Alien Breed
Alien Breed Tower Assault
Fallout
Fallout 2
Fallout Tactics
All 3 Gobiliins games
The first 5 Leisure Suit Larry Games

I'm guessing I might have no longer supported versions of these games and that is why they are doing it (similar to when a Steam game no longer has background images) but it's annoying me and I demand to know how to resolve it using some sort of sticky glue to put under the tile!

https://1drv.ms/i/s!ApWTaWnsmAkHgaRfF34D7zM3OzkNRA

There's a picture of the mischief!

Yep, it happens.

Then they figure out why and fix it. Then it happens again. Apparently it's a rather tricky thing to fix.


EDIT:
Also, you might try reporting it in the GOG Galaxy - Official Discussion Thread that is stickied at the top of the forums. The first post of that thread has some troubleshooting steps, too, and that first post is at the top of every page in that thread.

I have this too. In some, but not all, cases it seems to be related to games that have since been renamed in the catalogue, e.g. The Ultimate DOOM shows up with a blank until clicked, then it moves to Ultimate Doom, The.

I seem to have fixed it (or I may be speaking too soon) by doing a verify/repair of each infected game. Though this wasn't ideal for Fallout 1 and 2 because I then had to reinstall the unofficial patches that fix bugs in those games.

I suggest you contacting gog support.