I've manage to get a few other logs, hope these clarify things a bit more.
First I had Kodi to regenerate thumbs while leaving it completely alone and let it do its job without moving around or pressing any buttons. That time it didn't crash at all.
That log file is
here
After that I did the exact opposite and browse through the pictures while generating thumbnails, forcing it to load the thumbs that were still black at the time. While I was doing that, Kodi was running fullscreen. Suddenly the numbers in the debug info froze, indicating that Kodi might have frozen also. I switched to windowed mode, which caused Kodi to start responding again but after that the Kodi interface was shown in black, with white text:
First pic is right after windowed mode, second is when I had moved around so select another picture, third is after going back to the home screen.
Only the Kodi window was black, the Windows desktop and taskbar were as they should be.
Kodi seemed to keep running like this without crashing so I went to fullscreen mode again and started to browse through the pictures again until the debug info started to freeze again. Then switched to windowed mode to get it running. I did that a few times until I decided NOT to switch back to windowed mode when the debug info would freeze. It stayed frozen that way a number of seconds until I got a pop up from Windows that Kodi had crashed.
That logfile is
here (big one)
For testing I used the Estuary skin but when I first noticed the problem I was using the Titan skin. To rule out that thát was the problem I decided to stick to defaults as much as possible.
It seems that if I let Kodi generate its thumbnails and leave Kodi to work on it for ~15 minutes, it is OK. I seem to also be able to browse pictures when it is NOT generating thumbnails. However, it hates to be doing other things while it is generating thumbnails.
I also tested this in Jarvis but I could not replicate the issue there.