Intermittent Patch Cutout During Patch Changes

We've been using MainStage to drive our synths for weekly gigs for about a year now, and at times, when we change patches, MainStage will cut off all audio from the previous patch. This happens despite any relevant settings (we've left "Instantly Silence Previous Patch" unchecked, set the preferences for "Silence Previous Patch" from 5 seconds to 60 seconds and everywhere in-between, and turned off feedback detection in case something strange was going on there). It also doesn't seem to be localized to any specific patch, and we've not been able to recreate the issue during stress-tests, it just seems to happen whenever it wants to (which, incidentally, is almost always during live performance).

The problem seems to happen more frequently late in the set or during practice, but the CPU usage meter and memory don't seem to be popping above 50% at any point. We do use Playback for backing tracks, and keep our sound library on an external Thunderbolt drive.

We're using a circa 2012 13" MacBook Pro, which is upgraded to a quad-core i5, 16 gigs of RAM, and a 240gb SSD.

Anyone else seen this behavior, or any thoughts as to what might be causing the issue and how we can get around it? Thanks!