Unplugging the AVR did the trick. Thanks lovinthehd! I suspect this has something to do with HEOS. The AVR works directly with Spotify Connect, but things seem to get over-complicated when HEOS tries to take control of everything. Web searches turned up many past complaints of Spotify and HEOS not getting along. And the AVR wouldn’t come out of HEOS mode for some reason, until the reset. More research and experimentation is probably in order, but at least I’m up and running for now.