Unstable audio channel inputs in MainStage 3.1

Since upgrading to MainStage 3.1, I've had problems with the audio channel inputs. Here is the way I can reproduce the problem on multiple Yosemite Macs, tested with 4 different audio interfaces:

Open MainStage 3.1 Create an empty concert.

Create two patches that use audio input. (I have a Nord Piano that I run through the audio inputs)

Play patch #1, and get a decent input level.

Change to Patch #2.

The audio after switching patches sounds either glitchy or too loud or soft for about 10 to 12 seconds, then it settles down and works fine. Switch back to Patch #1. Same thing happens. Change from one audio input patch to another one, and it glitches for several seconds, then straightens out.

I've trashed .plist, changed latency, started from scratch with a new concert & no patches; and also imported old channel strips. I've changed computers, keyboard controllers, and audio/midi interfaces. It works fine in MainStage 2.1.3 and the latest version of logic, but is very unstable in MainStage 3.1. I'm testing on a 1-year old MacPro with 16GB of RAM & 500GB SSD, and a late 2009 iMac with 8gb of RAM. Both are using Yosemite 10.10.2.

Any ideas?