Did you enable Squeezebox support? If so, there are other ideas in this thread. Roon no longer sees my SB# or Transporter
Here’s what worked for me when I used an SB Touch:
I don’t know if this will work for you, and it runs counter to most advice, but it worked for me when my Squeezebox would disappear. I’d reinstall LMS and get it going long enough to establish a connection to the SBT. Once I could play music, I’d shut down LMS and restart Roon. Every time the SBT would show up after that. It’s like the SBT itself was having trouble getting on the network until I reconnected it to LMS. Your mileage may vary.