Seeing the same here. Quite annoying. Drum map could maybe use a little love too while they are fixing this. For example the Drum map manager or just even the individual mapping window (Map Properties) for each note looks like it was made in Windows XP and hasn't been touched since.
That Map Properties window always ends up behind the PRV as well.
And the pane that shows the keys of a piano to the left that sits vertically between the Drum Map display and the Controller display is really annoying. It make the controller pane difficult to resize without having to resize two different sections, over and over - especially annoying with this new bug of the zoom level not working right.
I guess they didn't test the Drum Map after making some of these other PRV changes.