I have nearly the Same Problems,
I have free trial membership. Roon core is installed on intel nuc, i7, 16 GB Ram, m2 ssd,128gb. Network avm 7490.
Have Connection from IPad with roon remote to Core, but very often interruptions. Have reboot everything, new installed, and try in a network from a frind with an other Intel nuc (same Performance).
Still same problems. Sometimes covers are shown, but no music is playing. Maybee the News Software failed?
Now it is not possible for me to lock in in Roon.
Maybe i try to often from different divises.