I think it depends on your video card driver whether this bug happens. I plan to fix it, but here are some workarounds you can try in the meantime:
- enable "Graphics > Surface Memory > System Memory"
- or, maybe disable "Graphics > Allow Hardware Acceleration"
- configure the game to run in windowed mode
- disable "Runtime > Performance > Store Video Memory in Savestates"
- disable hardware acceleration in your system display options troubleshooting settings, or maybe try changing other options that are specific to your type of video card
- try using older or newer versions of your video driver or a different video card, if possible
If any/all of those don't help, then revert the change(s) and I guess you'll have to wait for a fix. If one of those does work, keep in mind that some of them aren't saved settings, so you might have to re-apply it every time you start Hourglass.