Can't click title bar on mdi windows

WIndows Settings :: System > Display > Graphics
Optimizations for windowed games = Off

Also, below there is a list of Custom settings for applications
where you can set a GPU preference and enable/disable the optimizations for windowed games

Turning the optimizations off helped, it still feels a bit hit and miss, which is a significant improvement over always failing. Note this also fixed a problem I had with splitter logic using a region that was failing as well.

Thank you for the tip