MainStage 3.6.0 was released on March 14, 2022. This version of MainStage includes a bug that affects MainStage's ability to send MIDI info to external controllers, like the TouchOSC App.
If you've updated to MainStage 3.6.0 and use the TouchOSC App you'll notice that the Faders and Knobs within the App do not jump to the corresponding values in MainStage when you change Patches. While you're still able to control MainStage by manually touching and moving those faders and knobs in TouchOSC, MainStage isn't sending the right data to automatically update them when a given Patch is selected.
We have communicated this issue with MainStage's development team and they've confirmed that the bug lies within MainStage 3.6.0. We're confident the issue will be addressed in a future version of MainStage 3.6.
In the meantime, unfortunately, there is no workaround in 3.6.0 to restore this functionality.
If you rely on TouchOSC and have followed our recommendations to backup your previous versions of MainStage you can use MainStage 3.5 until the issue with 3.6 has been addressed.
If you have not already updated to MainStage 3.6.0, you should wait until these bugs have been fixed by MainStage's development team.
Since this issue is a part of MainStage 3.6.0 itself the most important thing to do for now is to let the MainStage development team know that you've been affected by it.
MainStage's Developers have directly requested that we ask all affected users to take these steps to report the issue:
1. With MainStage open in the Menubar select MainStage > Provide MainStage Feedback (pictured)
2. A web browser will open with a form to fill out.
3. Include the words "TouchOSC" in the Subject line (IMPORTANT)
4. Be as thorough as possible with the rest of the requested information. If you're not sure how to answer, you can ask us here at Sunday Sounds.