Thanks but that's not it.

The file plays fine and at the right tempo (85bpm). When I import it into another program, it shows the tempo as 120bpm.

The problem is when I adjust the click track (guide) tempo on the RC50 looper to the correct numerical value (85bpm), it changes the speed of playback as well (slower than 85bpm). This isn't the case for recording software because the metronome is independent.

I don't know anything about how wav files are saved but is there some master property file that can be changed?