Some App Instances cannot be focused So, assume I have 4-5 instances of an app running on different monitors (in this case, using DisplayLink Manager). Some times, some of the instances cannot be switched to anymore. When I right-click on the Icon in the dock I will see all instances, but with some of them nothing happens when selecting. Even in Mission Control the app instances are shown on the right monitor with the right state, but some of them just cannot be selected (they animate to kind of full screen and then disappear).

I am not sure what causes this behavior, maybe disconnecting the Mac from the dock and then reconnecting. Might the window(s) land off-screen?

In Windows this kind of stuff sometimes happened in multi-screen environments and you could do some trick to get the focus on the app and move it with the keyboard / mouse. In Mac I don't seem to find a way to recover these apps without killing them.

In my particular case killing the app has also the disadvantage that I only see one process in the Activity monitor, so I would have to kill all my running instances every time this happens. 

Is this a bug with Mac / DisplayLink Manager with multiple monitors? Is there any way to recover the apps?
So, I don't know if this will work always, but I found one workaround:


Switch to the non-showing instance of the app.
Switch to another instance of the app that shows.
Put this app in full screen
Switch to the non-showing instance of the app -> now it worked for me.


I am not sure if 1-3 have to happen on the same monitor, I will keep trying this out in the next days...