Running DS 2020sp4 on a high spec machine, Windows 10.

What I'm trying to do: draw a multi-segment line or polyline (or any other entity) while middle-mouse panning to another part of the drawing to complete the operation.

The problem: I can only pan once and then panning no longer works and no other operations are possible. I have to hit ESC, sometimes multiple times, to exit the operation and restore normal function.

This behavior is repeatable and consistent. It has been since at least sp2, I think. 

Is this just me or does anyone else have this problem? Any solution?