I usually work with three screens, and each has its own panel. Now, if unplugged the other monitors, the laptop screen doesn't panel task manager does not show me the apps. The task manager is there, right clicking on it show me the settings menu, but no programs are show.
If I reconnect the other monitors their panels will indeed show me the programs, but the laptop screen do not, meaning, the problem does not get fix, I have to restart.
I discover the problem has to do with the "Show only the task in this screen" option. For some reason, after the other monitors are unplugged, and even when they are plugged again, the laptop panel task manager doesn't "recognize" the programs running in its own screen, but unchecking that option will indeed make the task manager show all the programs.
Hope that's clear.