Playback freezes after creating project alternatives

[alexe]

Logic suddenly started to freeze on playback for a project I'm currently working on after I created two project alternatives inside the project (i.e. there are now three alternatives in total). The curious thing is that the first playback attempt after opening the project does work, and then consistently one of two things happens:

1) Either Logic freezes on the second playback attempt: When I hit the space bar to play the project back a second time, Logic freezes (spinning wheel).

2) Or the GUI already freezes on the first playback (playhead not moving, I can't press any buttons, spinning wheel, etc.) but the audio does play.

It's always one of these two behaviours that happens and Logic does not recover from this state.

Other projects have no issues and repeated playback works fine there, it's just this one project that freezes.

I have narrowed down the root cause to something related to the project alternatives functionality: When I export the affect project alternative to its own separate project, the playback suddenly works again, no more freezing.

Are there any known issues around the project alternatives functionality? Can I avoid this issue somehow?

With the current information, I will no longer use the project alternatives feature for the time being and consider it dangerous to use.

Edited November 26, 2022 by alexe

[alexe]

Update: I just remembered that I had created two project alternatives shortly before the playback freeze issue has started to occur.

I exported the affected project alternative as a new project and voilà, the playback works again.

So the problem must have been caused by some bug in the project alternatives functionality. Are there any known issues with that?

I will update my initial post above to reflect the new information.

[alexe]

One last follow-up to this in case anybody ever experiences a similar issue:

In addition to the freeze on playback, I started to observe that the project also froze on certain other events, e.g. when I tried to add or remove instrument tracks.

It turns out that some project meta data got corrupted, likely by the project alternatives feature.

I only noticed the corrupted project meta data when I launched Logic Pro without audio (by holding the Control key during launch) and tried to add a new instrument track to the project: I got a pop-up dialog that told me I had reached the limit of 1000 instrument tracks. The project did, of course, not have even remotely as many instrument tracks, so some meta data must have gotten messed up somewhere and this is likely what started causing all the issues I was observing. This pop-up only showed up in the no-audio mode.

I cannot say with certainty that the project alternatives feature is what caused the project corruption, but it seems quite likely, because the corruption occurred shortly after I had created the project alternatives.

My learning from this is that something is likely buggy in the project alternatives functionality and I won't use this feature again.

I should also say that exporting the affected project alternative did not solve the issue after all as I had first thought. The exported project was still corrupted. The only thing that worked for me to rescue the project was to recover a previous version of the project (before the project alternatives were created) from Time Machine and then selectively importing individual tracks and settings from the corrupted version of the project. It did not work to just import all tracks and settings from the corrupted project, because that would lead to the destination project becoming corrupted again. What a mess...

Edited December 18, 2022 by alexe