xlr audio and video out of sync

I am new to videography and I have been recording our church's services for the past six month. So far everything has been working great other than mistakes with exposure, etc I am recording with a BMPCC 4k and the audio is coming from a bus on our mixing board, into the camera through an XLR cable . Last Sunday and today the sound has been out of sync with video.

I recorded last week at 30 fps and had to slow it down to approx 26 fps to get the sound in sync. The battery for the pastor's wireless mic was very low so I wrote it off as a microphone problem (some kind of lag). Not thinking about that, this week I increased to 60 fps trying to get a better picture quality and now when I play it back, the video is moving easily twice as fast as the audio (the audio sounds perfect)

This happens in VLC player and DaVici Resolve Studio 17.1.1. I can't think of anything I've changed on the camera the last two weeks.

Any suggestions what I am doing to cause this?

Are you sure you didn't record as "off speed frame rate" ?

At this point, I am sure of nothing. I'll have to check the camera, which isn't with me at the moment.