I use NotePerformer and export audio a couple dozen times a day. A couple days ago Sibelius stopped exporting the audio. Instead of exporting a file it merely plays the score - which sounds fine - but nothing is exported. If I let it play to the end I receive a message that reads "MP3 conversion failed. Please check that a file with the name you have chosen is not open in another application and that you have permission to write to the chosen location." Choosing another file name doesn't help, nor does writing to another location, such as an external drive. So I don't think either suggestion in the message is the problem.
As far as I know, I haven't made any changes to the program or my computer, so I'm at a loss to figure out what is causing the problem. I use Windows 10. There was an update of some programs on my computer the day before the problem first occurred but the computer had already rebooted and exporting was working fine. So it doesn't seem like that is the problem. I checked to see if one of the updates was a Windows update, so I went to roll back the update but found the last Windows update was more than 10 days ago. So it seems it wasn't a Windows update that caused the problem.
Here are other things I've tried:
1) I updated from Sibelius 8.4 to 8.5. Nothing changed.
2) I re-installed NotePerformer. That worked long enough to export about 6 files then it stopped exporting again. I reinstalled again and it worked a few more times. After doing this each time I needed a file, this no longer worked after about the 4th or 5th reinstallation. So, that's a puzzlement.
Does anyone have an idea as to what might be causing this?
Thank you, in advance, for any suggestions.