Autoscroll and windows resizing bugs

I'm using AmigaOS 4.1 Update 2, pretty close to a clean install, on a Sam440ep.

If I go into ScreenMode preferences, and set my screen size larger than the default size, and activate "Autoscroll", and then I resize a window by grabbing the resize gadget, and I drag it to the edge of the display so that the screen starts scrolling, then the mouse jumps around to quite random-seeming locations.

Resizing windows on autoscroll screens is OK if you don't trigger the scrolling by hitting the side of the display.

Moving windows on autoscroll screens is jumpy but it works OK.

Resizing windows on large non-autoscroll screens is OK.

If I scroll by grabbing the screen using the left-Amiga+LMB combination, I get flickering and what looks like a picture of some other area in memory (garbage) for a moment. I haven't noticed this effect when autoscrolling.