As far as i can tell, then all should work fine in Ableton in a one screen setup. Are you sure, you turned the dual screen mode off?
I have a feeling this issue is about using dual screens with Ableton Live.
Do you have issues using other third party plugins? If so, then i don't think, it have anything to do with the plugins.
The dual screen issues i know of, have as far as i remember allways been about something that needed to be done or fixed in the DAW.
If you use high resolution, then that perhaps also can have something to do with the issue. You can try to test it.
It's good you contact the supports.
Good luck.