Hey Dan, this worked for me when my Squeezebox Touch would fail to show up in Roon. Might be worth trying on your boxes. 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 of course.
You might check out this thread as well: Roon no longer sees my SB# or Transporter