If you are having trouble with a song specific patch from Sunday Sounds, first, go ahead and do a full restart of your computer. If some channel strips sound different than in the demo video then you’re most likely missing some of the MainStage Sound Library content. Use the Sound Library Manager in MainStage to download the additional sample library content, restart MainStage, and try again.
You'll want these downloaded:
If the mod wheel doesn’t function as in the demo video, make sure your mod wheel is sending on midi channel 1. Make sure that the patch you downloaded doesn’t have any special installation instructions (available on the product page where you purchased the patch- this case is very rare)
1. Try using the patch in the stock concert “Keyboard Minimalist” to see if that helps? That would indicate the problem is related to the concert file, most likely the mod wheel programming.
2. Move the mod wheel up and down a few times then try again and see if it changes
3. Are you using a mod wheel or did you assign it to something else like a knob or fader? It’s possible you may have missed a step so the mod wheel in your concert is not functioning correctly.
4. You may be missing samples, double check your sound library again after a restart.