There is a problem with iPadOS and certain device-monitor-adapter-combinations which results in my app not recognizing some monitors or big black bars on the monitor. This has happened to about 26 users so far. If you have encountered this issue (your connected monitor shows the text 'no monitor connected') please follow these steps. If you have not encountered this excat issue, please do not follow these steps and take a look at the FAQ.
Close the app (in multitasking), disable your internet connection and VPNs. Try connecting to your monitor via cable again. Does it work this way?
2. Solution Go to the app settings > advanced settings and then activate the toggle with the label 'use when the app does not work'. After that restart the app.
If the monitor is still not being recognized, then please go over to reportaproblem.apple.com and request a refund (you need to request a refund from Apple directly, Apple does not allow me as a developer to give a refund). At this point I cannot fix any of the issues lying deep inside of iOS and iPadOS. I hope Apple fixes this with an upcoming iOS update.