Displaylink only allows one external monitor when in 90 degree rotation

[rboerner]

Originally Posted by slockshin

Displaylink will not show a second monitor (sees in Displaylink monitor, but monitor is all black).

Monterey 12.0.1
Apple M1 Max
2 - Benq PD322OU Monitors

Displaylink and OS Display control see monitors
Both set to 90 degree rotation
Monitors work when switching cables
Must be a software issue, but only one Benq PD322OU renders...the other stays all black

I myself have not encountered the behavior you describe, however one thing that did jump out is that you are running macOS Monterey version 12.01.

As of today, the latest version of macOS Monterey is 12.1 (notice the absence of the zero).

If you update your system to the latest version of macOS, does that change the behavior?