No matter what settings I use in Mission Control or in TotalSpaces2, LR (latest version) keeps opening on the main screen and I have to move it to the secondary monitor each time I restart it or change catalogs. It is irritating but also problematic in that LR seems to get lost on occasion when I use the main monitor for full sized images and will seemingly randomly put the full frame image on top of the main LR grid and control screens (on the secondary monitor) which forces me to close LR to get back to normal. So far I haven't been able to figure out any sequence that causes this to happen but there probably is one.
1. Tried with the possible combinations of "Displays have separate spaces" and Spaces assignments available by right clicking the program's icon in the Dock.
2. Lowering the position of the secondary monitor in Display Arrangements (a strange suggestion via the Internet)
3. Very politely asking LR to behave like all of the other programs.