I opened up an animation file from 2020 in the newest version of photoshop. I can see the different keyframes when I move the playhead, but the play button is disabled. Does anyone know why this might be?
Inexplicably, the Apple silicon / M1 version of Photoshop does not support animation. To get around this, you should install a legacy / intel version of photoshop. The animation palette will now be functional and you can complete your project in that version.