Drag and Drop won't drop sometimes when running Parallels - Windows

Hi,
I've noticed that sometimes while Parallels is running (I haven't yet found a pattern for it), my systemwide drag and drop gets weird, such that if I drag something, it never drops, even when I let go of the mouse. I get a system-wide drag and drop problem where the drag action "sticks" and won't let go of the dragged object. Has anyone else experienced this?
Some users have this problem on a Windows terminal server; drag and drop only works again when you log out of the TS and log in again. Unfortunately, this is very tedious and disrupts productivity when working.
I have seen that there is already a forum entry https://forum.parallels.com/threads/drag-and-drop-wont-drop-sometimes-when-running-parallels.107326/ on the problem - but unfortunately there is no solution listed there.
I really would appreciate some help!