Premiere playback shows no video.
The "source" and "program" panels do not show me the video.
I had placed the "program" panel on the second monitor.
Even if you reset the workspaces and preferences (starting with presses by pressing shift + alt) I could not prevent it from opening like this.
This is the way I used to solve the problem, but the bug remains.
I changed the setting:
Window> Workspaces> Import workspace from project (no set).
I reset the workspace and the panels were all in the main monitor.
In this way, I avoided that the "program" panel would open on the second monitor at the next launch of Premiere.
I restarted Premiere.
The panels were all in the main monitor.
The video could be seen.
Hope this help.