MAutoAlign “unsyncs” items during rendering in Reaper – MeldaProduction Forum

I did a recording of a choir recently with a main mic and another recording from someone else’s machine halfway down the church. Managed to sync the two stereo recordings perfectly in Auto Align, but I’ve noticed that after rendering, they are no longer in sync.

Have gone back into the Reaper project and they are in sync when I play it there, so I’m not entirely sure why the audio appears to have gone out of sync during the rendering process.

Can anyone suggest some experiments I could try/ something I’m doing wrong?