Unable to export sound files

This morning I went to export soundfiles (.wav and .mp3) from two scores I had written back in March and was unable to do so, constantly getting the message "Cannot write into C:/Users/e----/Documents/MuseScore3/Scores/(filename).wav." Is there something that I'm doing wrong? I was able to export sound files from (other) new pieces about 2 and a half weeks ago. The only thing I can think that might have affected this is that I downloaded Sonatina and Aegean Symphony Orchestra 3 weeks ago, found that it was changing all the sounds of my pieces to piano, so I deleted those soundfonts, and uninstalled and reinstalled MuseScore, which seemed to correct the issue. Could that be what's making it impossible for me to export sound files? And, if so, how do I fix the problem? Thanks in advance.