Multiple Parts in MuseScore 4

So I'm working on a score in MS4 transferring an old jazz tune (5 bone parts, 5 trumpet parts, 5 sax parts, and a rhythm section) when something apparently became corrupt:

1. I saw 8 parts for Trumpet 1 and 3 parts for Trumpet 5 all named "Trumpet in Bb 1."
2. Musescore would hang for 60 seconds when I attempted to close and restart it due to this.
3. I managed to renamed all the Trumpet 1 parts to Trumpet 1, Trumpet 1a thru Trumpet 1g and did the same for the Trumpet 5 part (Trumpet 5, Trumpet 5a and Trumpet 5b.)

4. Musescore now closes normally (quickly).

5. However now when I go into File, Parts I still see all the extra parts.

6. When I open MuseScore, open the chart in question and hit "I", I see the correct number of parts ( 5 trumpets) but again all the trumpet parts are labeled "Trumpet in Bb"

I've included two jpegs - one labeled "Parts screenshot.jpeg" and one labeled "Instrument screenshot.jpeg" so one can see what I'm experiencing.

Many thanks in advance for the help in solving this.