Hi Michael, welcome to the community.
Presumably both your MacBook Pro and your iPhone are accessing the Bartok via the same WiFi Access Point? Since your iPhone sees the Bartok, that suggests both your dCS and your network are just fine, so the problem must be with the Macbook/MacOS. There are a couple of things you can check on your Macbook;
- Make sure it doesn’t have any funky firewall settings
- Likewise “Screen Time”, best to turn it off
- Also, try launching the Bonjour Browser app from you MacBook Pro; select your local network, see if it finds the Bartok when forced to search. You should see a window like this;
I can’t remember if Catalina comes with the Bonjour Browser, if it doesn’t try the free “Discovery” App from the Apple Appstore, it does the same thing.