Chromecast streaming stopped working

I've been successfully casting to Chromecast devices attached to a TV for a few years.  About two weeks ago, casting to a Chromecast device only shows the preview thumbnail of the show, and neverending 3 animated dots.  All selections play fine on a PC and in the Android Stream app, but when sent to the CCast, it never starts.  I've tried 4 different Chromecast devices, including a new one just purchased.  All with up-to-date firmware.  Anyone else seeing this problem recently?