I found my devices to often chase the server with 2 LMS’s running at the same time and so some units would connect to one and some connect to the other.
I found similar with 1 LMS and 1 Roon.
I have LMS setup and up to date looking at the same music, but turn it off when using Roon.
Using LMS only you can disable LMS support with one little on/off switch in Roon.