Audio desyncs and is offset after Davinci export -

Hello!

Issue: After exporting from DaVinci Resolve 17, the audio is offset by 5-6 frames

Short version: It happens when you Drag&Drop an audio file onto the "Audio 2" track under certain conditions

Image: feen(dot)us/5iikgz.png

The issue seems to occur on larger projects, but it has also been reproduced on smaller renders.

Out of 20 attempts to reproduce the issue on a new project, only 3 were successful following the exact same repro steps written below.

However, using a previously saved project where the issue was present where we "fixed" it using a workaround, we managed to reproduce and re-trigger it 100%.

Here is the following info, hoping it would be of use to the QA team, as well as the users who need a solution to save their projects.

For a New Project

Repro Steps:
1. Import ClipA and its corresponding separate audio track AudioA (which comes in the form of a WAV file, recording with a different microphone on the film set) into the Media Pool
2. Import ClipB and its corresponding separate audio track AudioB (which comes in the form of a WAV file, recording with a different microphone on the film set) into the Media Pool
3. In the Edit tab of DaVinci, sync ClipA with AudioA, and ClipB with AudioB, using the "Auto Sync Audio - Based on Waveform" function

4. Drag&Drop (important!) ClipA and ClipB onto the timeline, on the "Video 1" track, with their respective audio tracks on "Audio 1" track
5. Make sure they are in sequence, with no gaps, you are free to adjust them, trim them, shrink them
6. Go outside DaVinci but do not minimize it, pick an audio file and Drag&Drop it back into DaVinci, without letting go of your mouse button keep dragging the audio clip over the "Audio 1" track, which will make the waveforms react to it, then drag it below which will automatically create the "Audio 2" track <<< this is what triggers the bug

7. Render video (any format, we used AVI Uncompressed YUV 422 10-bit codec) and notice the delay in audio. If you add an audio cue on the "Audio 1" track, like a blooper reel beep, alongside a visual aid on a new video track "Video 2" like a solid color, it will help you see the offset better. However, this might interfere with the reproduction of the bug.

Image with audio cue inserted: feen(dot)us/hlv1p5.png

The difficulty presented by this bug is the fact that you can't be sure exactly which mouse motion over "Audio 1" track triggers the issue.

For an existing project

Repro Steps:
1. Go the the Edit tab
2. From outside DaVinci, without minimizing it, drag a new audio file across the already existing audio tracks, then drop it in a new formed audio track.

Fix 1
- Save your project and restart DaVinci. Once you reload your project, do not modify anything and go directly to the render tab, trying to modify as little as possible (perhaps a render preset will help you better)

Fix 2
- Just delete all the audio tracks except the "Audio 1" track and when reimporting the audio tracks, manually create the "Audio 2" track, afterwhich right click the clips in the Media Pool and select "insert" in the timeline

Observations
- The issue only occurs using Drag&Drop
- It seems like there is a higher chance of occurring if the "Audio 1" track is really low on the screen, which leaves a very small gap where the user can drag the new audio to form a new audio track. This makes the dragged audio "flicker" and spazz out between "Audio 1" and the newly formed "Audio 2" tracks
- The issue seems to not occur if the video clips keep their original audio, instead of the user replacing the audio using the Auto-Sync function
- Visual Effects, Color Grading, Audio Effects (simple and VST) do not seem to affect the issue in any way


I wish there was a definite 100% way of reproducing the issue on a new project but, oddly enough, it seems to depend on your exact motions when you Drag&Drop new files onto the timeline and the source of the files (Media Pool VS directly from the desktop/outside DaVinci).

If anything, at least the two fixes provided should prove useful, or a base that would lead towards a better fix