I consulted a few of my colleagues for the issue you are experiencing and they confirmed that because the Pixelbook is using a Sandbox Firewall, it is almost impossible for Roon to communicate properly with the Core.
You can read more regarding this issue in these links:
As you can see in those threads, some users have reported that connecting to Roon by fixed IP temporarily resolves this issue but the sandbox environment in general prevents a stable connection from reaching the Core through the firewall. I haven’t heard any updates regarding those threads but you may want to ask users who reported success as to what they changed in their setup to get it working. Hope this helps.