Audio mixdown changes sample rate of original file

I have a recorded WAV file in my project, recorded at 48 kHz and 24 bit. I did an audio mixdown to MP3 with the correct sample rate. After the mixdown, I went to play back the original WAV file in the project solo’d out. It played correctly for a second, then I got a short burst of white noise. Immediately after that, the file started playing back, but at a different sample rate. It’s about 50% slower and pitched down, as if the sample rate had completely changed on the original track. I did nothing to resample this file, and the MP3 file was not playing at all. Anyone have an idea s to what could cause this? Thanks for your help.

I redid this process, closing the project file I was working on (not saving it), and re-opening it to try the bounce again. I followed the steps again, and the same result: The original recorded WAV file played correctly for a second, then began playing at a much reduced(?) sample rate. I have no idea what could be causing this.