Waited 30 minutes for a call back - the caller disconnected after just a few seconds, but has not called me back. Why no callback after the disconnect?

We do not know.  The user forum is not a conduit to customer support or to TurboTax Live.  We have no way to help with that.  Initiate another call.

You are posting from TurboTax Live.  You can arrange for the Live help you are paying the extra fee for with your questions from  5 a.m. to 5 p.m. Pacific time Monday - Friday.

https://ttlc.intuit.com/questions/4124827-how-do-i-connect-with-a-tax-expert-in-turbotax-live