One more update - I restarted the mac mini server, I deleted and reinstalled MC 30.0.45 on the Macbook pro. I opened MC and connected to the remote library. The load takes about 10-15 seconds, after which everything was there. I added an album to the server. Did a refresh on the client and the new album didn't show up. I did a "sync" and it didn't show up. I shut down MC on the macbook and when I went to reopen MC, it could no longer connect to the server version.
It's like a fresh install connects long enough to get the current state of the library - but after that, it is no longer able to connect. I'm happy to send someone a full error log directly, but since it contains sensitive info I don't want to post it up here. Let me know - this is baffling. Never had this issue between my macbook and windows server - so not sure if this is an issue between MC for mac or what.
Thanks in advance for any assistance.