Using A8 commercial, but not region_set.
What you cant see in the video is that this "side effect" gets faster and stronger with every additional time you scale (eg pick an arrow) - not dependent on how long each individual scaling process is. Don't know if this helps you find the error

I will try again, although I already did what I could - started with a blank level and so on. Anything I could possibly do wrong, for example when compiling the map?

Thanks for your time