To illustrate what I said about the meters during playback, here's a screenshot taken during playback of a project that won't play audio. Note how track 1 clearly has audio in the top half of the screen, but there's no activity at all in the meters below.
I watched the video in the first reply and there were no changes to be made. That's why I think this is a bug because there does not appear to be anything different about the projects that suddenly stop playing audio, and I can playback any other project that does not have the audio issue just fine, either with Bluetooth earbuds or with computer audio.
If this isn't a bug, it should be something that can be resolved by changing a setting within the project, but I just cannot find anything different in the projects that have this issue.
If anyone else has any idea what could be happening here, please let me know. I have completely lost audio on a number of projects as a result of this, and it seems my only option is to start over on those... which is frustrating when I've spent days editing and mixing a project until it's almost complete.
Thanks.