1. What happened
In the process of implementing a resolution dialog I stumbeld upon this thread: https://forum.unity.com/threads/switch-monitor-at-runtime.501336/page-2
As well as this github repository: https://github.com/Unity-Technologies/DesktopSamples/tree/master/MoveWindowSample
Trying this on my multi monitor setup that uses the exact same benQ monitors, the monitor native resolution is not recognized on the secondary monitor. It also seems that when trying ExclusiveFullscreenMode on the second monitor it only outputs fullhd instead of the native 2560x1440 (although the ui displays something differnt). This is in line with player reports (from earlier titles) we received from customers who tried to run the game on their secondary monitor and were missing the native resolution.
2. How can we reproduce it using the example you attached
1. Have a multi monitor setup
2. build the project
3. adjust the resolution on the primary monitor
4. observe everything works
5. change the display to a secondary monitor
6. observe that the native resolution is missing from the list
Since this might be hard to re-produce on different setups, I've attached video evidence of the described things happening.
Note: CQA was unsuccessful in reproducing the issue using DELL U2518D 2560x1440 60hz using 2 Display Ports and an HDMI on Windows 10