Why is mp3 processing taking too long?

I created a simple presentation. I uploaded a mp3 file for narrataion. The file uploaded with no errors. Aftwerwards, I am told to wait for the mp3 file to be processed, and that I am to be redirected to sync tool. I tried that several times. Each time tried a different source for the mp3 file, or presentation. On each tryout, the mp3 processing did not complete even after more than a hour.