Adding Artwork in iTunes adds "extra" material to the music

When I use Add Artwork to edit multiple tracks at one time iTunes will randomly add music on to the the file. For instance, when you listen to playback, you hear the end of the song then maybe a 2 second portion of the end of the song added on. It does not seem to happen when adding artwork to one song at a time. I have ruined over 40 songs and will either have to use time machine to go back to before I added the Artwork or re-edit. =((

Here are screenshots of after adding artwork to one song individually and after adding artwork to two songs at once. When I added artwork to two songs at once iTunes added 15 seconds on to the song in the screenshot. It seemed to add 9 seconds to the other song. It will add material on to the songs each time I change the art work. It does not necessarily add the material to the end and may insert the extra material between the "original" song and another randomly added portion. YIKES

These were songs recorded at my church on an Olympus recorder and trimmed, compressed and Noise reduction done in Audacity 2.1.0. I am using a MacMini(Late 2012) currently with Mojave 10.14.6 and iTunes 12.9.5.5.

This problem seems to be confined to Add Artwork. If I only edit the metadata text it does not change the song.

HelP!