Hey there!
I don’t want to bring some sad news, but it’s been reported for a long time, that Roon has issues with storing database on NAS. On top of that, NAS doesn’t provide that fast speed for picking up files and has issues with gapless playing. It’s not that much of Roon limitations, rather than NAS protocols.
I’m not saying storing music for Roon on NAS is a bad choice, all I’m saying there way better options – including internal storages of Roon Servers, SSD and SD card with adapters