The verticall scroll bar disappeard in 2020.11.02.00 early access and the regular version. See attached picture, right side.
Input for bug fixing:
I added on my second screen (F11 shortcut one) a new robot skill, the very basic script (https://synthiam.com/Support/Skills/Scripting/Script?id=16089). After that I vertical scroll bar was gone.
Tried various options like going to older save but that seems not affected as well.
The scroll bar is visible on the first (F10)and third (F12) screen.
Adding the same script robot skill on the first (F10) screen was possible and I could next move it to the second screen. When I deleted it over there (because I suspect the script created some more problems) the vertical scroll bar is gone again.