Audio File Delay in Summed Track Stack Only

[Gabbagool]

So this is bizarre-

I have a project with summed track stacks containing audio stems (All drums, all bass, all music etc). Deep into mixing this project I noticed that one of the audio tracks in the music stack is ever so slightly off timing wise. It’s super obvious because it’s the first note that plays in the song, a super precise transient.
 

Can confirm this by moving the stem outside of the track stack and the timing is fixed. 

The location of the audio file doesn’t change on the timeline, it’s the same stereo track and waveform whether it’s in the stack or on its own.

What’s weirder is if I go back to a previous project alternative, the audio file timing is fine inside the track stack. 

Id like to use this current alternative, instead of having to go back- was deep into editing vocals on this version. Didn’t even touch the music stems…?

I’ve tried disabling and enabling core audio, etc in the settings but his doesn’t fix the issue.

Any ideas? Thanks for any help!

[scg]

The behavior you describe is typical of Logic's latency compensation issues. However, I've never known that to manifest with audio files, so I'm not sure if that's what's happening here.

If I were troubleshooting this, I might duplicate the track so I had one track in the stack and one out, and then play them together and listen for phasing or obvious out-of-time-ness, just as way of clearly demonstrating the behavior. Another thing to check would be accumulated plugin latency on the problem track, and on the track stack. A possible experiment would be to (backing up thoroughly first of course, just in case) create a dedicated project or project alternative and remove (not just bypass) all audio effect plugins, and see if the behavior persists after that. That might provide a clue as to the cause.

These are just speculative ideas. As always, it may be that this is an issue someone else is already familiar with, and that they'll be able to provide an answer.

Edited May 12, 2023 by scg

[scg]

Another thing to check is region delay. If you're moving the same track in and out of the stack, or moving the same region between tracks, then it presumably wouldn't be that, and region delay isn't something you'd be likely to change accidentally. But, I'd still include it in troubleshooting, just to be thorough.

[Gabbagool]

I found the culprit- Using Wavesfactory TrackSpacer Version: 2.5.10 sidechained to a bus is causing the initial latency. Only when I remove TrackSpacer entirely from the summed stack (not just disable it), the latency goes away. This is weird to me simply because I've never run into it on any of my projects before, especially this one with many alternates and iterations.

Seems the solution for me is to just make and use a different track stack  using TrackSpacer differently.

FWIW I'm using Logic 10.6.2 . Seems like this buggy behavior of latency from sidechaining to a bus might have been solved with 10.6.3

https://www.reddit.com/r/Logic_Studio/comments/oerpkr/odd_playback_latency_when_sidechaining_to_a_bus/

Thank you for your help!

EDIT: Haha okay perfect now it works intermittently with sidechaining a bus. Oh well.

Edited May 12, 2023 by Gabbagool