Trying to use multiple screens does not go well. I found that all windows that aren't in the main window UI don't adjust right, stay in place and tool tips stop working. Also with this set up any splash screen gets lost needing to Esc out to continue. Also any issues warning get lost when opening a file. 

I went through these problems a while back. Various windows not showing up.
I use three monitors on Windows 10.
I believe what was throwing things off was not having a uniform "scale" (under "Scale and layout" in display settings) across the monitors. Once I made them all the same (e.g., 125%), most of the issues went away.