Audio Editor importing voices at different playing speeds!

I have produced a series of courses and just have the audio to add. My SME made recordings which I have in MP3 format and I just need to import them a slide at a time then synch. It worked perfectly for 2 courses, but the third one is weird.

When I import a file in audio editor it imports and plays back in slow motion, other files are speeded up. I have tried multiple times. Closing and restarting, even shutting down and rebooting. The files play file on their own.

On a longer course I had a different issue of the waveform not matching to the audio, making editing out errors very difficult.

Any ideas what is causing this and how I can fix?

Thanks