open blend file:
and then try to press "+" or "-" or press with mouse on the
magnifying glass.
The zoom will not change.
pressing 0 or the cam symbol makes it move again.
and also if rotating it a bit, then it can be zoomed a bit.
UPDATE:
when pressing "-" and holding it for a longer time, the "zoom out" again works.
but on pressing "+" the "zoom in" does not work
Blender: 2.90 and 2.91 (alpha)
Win10PRO v2004 64bit