II continue to get this error, when the files clearly should sync. Am I doing something wrong? I think I am doing the same exact steps as I've done when it did work. Syncing clips manually makes have Premiere Pro about worthless - this is a constant in my workflow.
Are you clips linked? They are all different colours. Does it work if you select just the clip on A1 and A3 for example? Which track are you using in the Synchronize Clips dialog?
I used to get super irritated by this... and then I discovered that, if I go to the Sequence menu and choose Render Audio first, and then sync with audio, it works. I'm sure there's a technical reason why this is a "feature" and not a "bug". Whatever. Hope it helps.
Tried rendering first (took 15 minutes), and it still failed.
A2 doesn't show any waveform at the beginning of the clip. Go into that, and set audio gain to max all peaks to maybe -6dB. It will probably work then.
So sorry the previous suggestion didn't work for you... it does for me. Waiting 15 minutes and no result must be super frustrating.
I don't know what your media is like... it could be that there actually is a slight discrepancy that is enough to throw the algorithm off. Like audio drift? (One device gradually slows down the audio, barely perceptible unless the file is really long.) Or... maybe one mic was very close to a voice and picked it up clearly but the other mic was far enough away that it just didn't pick up... or whatever. If the two audio tracks are "different" enough for PP to not match them... maybe try this:
1. Make a copy of the sequence (just in case)
2. In the sequence copy, trim your two audio tracks back to a very short span where each picked up the same audio clearly (maybe just the clap in the beginning, or a section where a few loud bursts happen). So basically, if your entire sequence was (let's say) 2 minutes long, trim the beginning and ending of each clip to just that span of 15 seconds (let's say) somewhere in the middle where the audio was clearly picked up by both mics.
3. Select both clips and synchronize with audio.
4. After syncing, they're lined up correctly in the timeline, and you can "untrim" them both out to their full length.
I know this works... but I do wonder if after all that it would have been easier to just manually sync the clips. Probably same number of clicks. ?
Synchronizing only the audio aside from the video part should work. Then move the videos back to their respective audio tracks since they are the same length. This worked for me.