Our application is trying to read all resolutions of an external monitor. We have observed that, for the external monitor there is a mismatch in resolution list in our application and the resolution list in system settings. We are using the apple API "CGDisplayCopyAllDisplayModes" to read the resolutions.

Macs do not support Multi-Stream Transport (MST), which prevents from using a single DisplayPort or USB-C port to daisy-chain multiple external monitors in an extended display mode. So the the virtual multiple display modes are not working correctly on Mac.