Error importing from PluralEyes: This item is not on an edit frame boundary

I'm attempting to import a synced project back into FCPX 10.4.4 from PluralEyes 4.1.8, and keep getting this error message: "This item is not on an edit frame boundary".

This is extremely frustrating, as everything syncs properly in PE.

I created the project in FCPX with three sequential MOV files recorded with a Canon T3i, one MOV video created with an iPhone 6s, and one WAV file recorded with a Roland digital recorder.

The WAV file records audio of the entire event, filling in brief gaps where the camera stopped and started (due to a 12-minute video limitation imposed on the Canon).

I exported the FCPX project as an XML file, imported it into PE and synced it. PluralEyes spaced the Canon MOV files across the WAV file to neatly account for those gaps, and synced the brief iPhone MOV file where it belonged at the end of the project. Everything looked great and the audio all synced properly.

However, when I output the XML file and imported it into FCPX, the problems began. I'll attach a screenshot of the FCPX error notice, but it contained multiple instances of the error message.

I've tried multiple variations of the export/sync/import process, in case one particular file was causing the problem. But the error occurs every time.

I just need this thing to work. Is there any way to make it do so?

Thank you.

I had this problem before but can't recall what I did to correct it. Something at the back of my brain tells me there was a bad / corrupt frame in one of the videos. I believe it presented as a completely black frame. What I did to find it was export Vid 1 alone synced to audio then Vid 2 synced then Vid 3 synced. Since the only constant was the audio track that hepled to narrow down where the funky video was.