Hello,
This happens whatever the style I try to load.
In my case, the first 12 Bars are in a Bluegrass style: _BGBDBS8 Fast Bluegrass Eights 260 Banjo Solo, I reduced the Tempo from 260 to 230.
At Bar 13, I made a style change for the rest of the song: _BLUGRF8 Classic Bluegrass 8ths 260 Fif. I also reduced the tempo to 230.
Again, the name of the style effectively changes at Bar 13 but I keep the same sound.
All the tracks are unfrozen, I checked it.
About "What add-ons ...", I am sorry but I don't know what to look at. This is confusing.
Best regards