Black box covering display when I try to use 'Browse All Versions'

I have my iMac hooked up to a second display and I often use Pages on the second display while taking a course on the main display. If I try File>Revert to>Browse all versions in this configuration, Pages moves over to the main display and then 'Browse all versions' opens with a black box covering most of my screen. This also happens if I have Pages open on the main display with the second display turned off.

(This also happens with textedit, but it does NOT happen with Numbers. For Numbers, the second display goes black and Numbers' 'Browse all versions' moves over to the main display, no black box.)

If I disconnect my second monitor (NOT just turn it off), Pages 'Browse all versions' works as normal. The black box seems to be the second display going black over the main display (if that makes sense). With the second monitor connected, the second display starts to go black and then it comes on again as the black box appears on the main display.

Any others with this problem? What is the issue and is there a better way of dealing with it then disconnecting my second monitor?

Pages: version 11.1 (7031.0.102)

Numbers: version 11.1 (7031.0.102)

TextEdit: Version 1.16 (365.2)

iMac (Retina 5K, 27-inch, 2019)

macOS 11.4 (20F71)

3 GHz 6-Core Intel Core i5

8 GB 2667 MHz DDR4

Radeon Pro 570 X 4GB