Audio speed not matching between original music track and recorded music [FCPX]

I recorded an outdoor dance recital. I’m trying to lay the original music tracks that the dances were performed to over the recording (it was a windy day and the camera audio sucks).

When I go to sync the original track to the recording in a multicam clip, the automatic tool says it cannot sync. When I line the clips up manually using the sound waves (single point match at the beginning), they are out of sync almost immediately. By the end of a three minute song they’re off by as much as two full seconds.

This is my third year doing this event and it’s always been an issue, but never this bad before. Usually I can cut the original audio in a couple places and lay them over each other so it’s not noticeable. I can’t do that this time, I’d have to cut it every five seconds.

The annoying part is SOME of the clips DID sync using the automatic tool. The show was performed in 5 acts, the last act was after sunset and the original tracks for the last act all synced fine. I have no idea why???

My cameras recorded 48kHz and the original tracks are all 44.1kHz - that discrepancy would account for SOME sync drift, but not something this extreme.

What did I do wrong? How do I fix it? How can I make the original track match the recording?

The only thing I can think is that it was a very hot sunny day and that may have effected the sound waves as they were being recorded?

I’m going to try changing the speed of the audio clips to match but I’m worried it will distort the sound quality.