Thanks for humoring me and giving me a problem to tinker with this evening 
I ruled out everything I had in mind initially and began to suspect it was a polyphony limit after all… but it turns out that’s not totally right either!
I was able to eliminate the clicking by assigning only 12 of the 24 voices (EDIT: I initially assigned all 24 which fixed it too; 12 just rules out polyphony issues):
- auto
- 1
- 1
- 3
- 1
- 3
- 3
- auto
But the REALLY interesting part is that, if the sequencer is running while you’re changing the number of voices allocated you get the same clicking/crackling we were hearing before.
So I suspect this is some sort of issue with how auto voice allocation is handled. Not taking bets though.