Viewports are not regenerated when zooming

Hello, everyone.
I've been using BricsCAD since version 15 I guess. Recently I upgraded from 20 to 21 and noticed strange behavior when working in viewports in paper space.
It seems that viewports are not automatically regenerated like in V20. When zooming/moving with the mouse, I always have to regenerate manually.
It is very annoying when zooming out with LWDISPLAY on. Sometimes it seems that after every change (changing layer, deleting, drawing, etc) the viewport has to be regenerated.

regenauto does not work.

Best regards,
Dirk