My Samsung Galaxy S8 (Verizon) found the Rhythm+ in the Zwift pairing screen, and the color on the HRM changed indicated a BLE connection, but the Zwift app said “No Signal” and would not read any HR data.
This was in run mode. My Stryd footpod paired fine and did not drop at all during my entire session.
I assume this is one of the issues specifically called out in the release notes, but I figured it could be helpful to have a specific device combination to troubleshoot.
FWIW, the ant+ on my Garmin 920XT picked up the HR no problem (as well as the Stryd).