I use two external monitors connected to my closed MacBook Pro. When I use Royal TSX it is in Full Screen mode on the second monitor.
When I restart the OS and when I restart Royal TSX it appears in Full Screen mode on the first monitor. The expectation is what it will stay on the monitor it is initially assigned to.
Other applications I use such as Airmail, and Apple's Numbers will follow this convention.
I can reproduce this error every time I restart my computer or quit and reopen Royal TSX.
When I restart, I will go to the Apple menu and select Restart from the menu with all my applications open. When everything comes back up, Royal TSX has shifted from the "right" monitor to the "left" monitor while still in full screen mode. The left monitor is the one that has the Dock if that makes a difference.
When I quit, I will just use Command+Q when Royal TSX is the active application. I'm not specifying any modifier keys. Royal TSX will go from being maximized on the right monitor before quitting to opening full screen on the left monitor after being opened again.
I can see when I hold down the Alt key while the Royal TSX menu is open that the bottom command changes to "Quit and Close All Windows" but this is something I am not intentionally triggering.
I cannot reproduce this here. Does the issue only occur after a reboot or every time you quit and restart Royal TSX?
Do you quit Royal TSX using "Quit and Keep Windows"?