Piano V volume drops randomly from the saved level in my preset in MainStage

I created a custom preset from That Old Tyme upright in Piano V3 in which the only thing I changed was to turn the volume all the way up (see photo).

I use it in MainStage and always after a certain period of playing the volume falls back down to the That Old Tyme default (about 25 percent lower). I use lots of other V Collection instruments in this MainStage concert and this is the only preset doing this. Any ideas why this would happen?

It does not seem to revert to the default volume when I play my preset in Piano V3 standalone mode, only in MainStage (on a MacBook Air running Monterey).

Image 5-16-24 at 11.29 AM