Server Version#: 1.18.7.2457
Player Version#: 1.6.3.1009-57cf57c8
The issue described in this closed thread is still happening on the latest version;
The workaround described still works (Deleting Plex folder from AppData\Local) but the actual bug still exists.
Can be reproduced with dual monitors with different resolutions, may not happen on dual monitors with same resolution.
If you open the app on your primary monitor it will open fine. If you drag it to the second monitor and then close it while it’s on the second monitor, it will try to open back up on the second monitor and will just display a small white square and never actually launch properly.