The latest version of the RPi OS which was issued on 8th November has seriously broken Pi Presents. As an amateur developer I get no notice of these changes.
Fortunately the previous version of the OS, based on Debian Buster, is available and should be used for Pi Presents Beep and Gapless. It appears Buster will receive security updates and bug fixes for a few years. The OS is available here:
For the technicaly minded Bullseye has removed mmal/omx and video players that rely on it – omxplayer and the VLC facilities I use to embed videos. It has also replaced FKMS with KMS which alters control of the displays.