I have exactly the same issue. It's 1 single track and I've isolated the issue. Deleting all MIDI events on this track, solves the issue. It isn't a freeze by the way, but my CPU spikes to 150%. I've already tried so many things, like the GPU performance tweak for OSX, disabling iCloud, but this clearly seems to be a S1 bug...
I'm gonna dig a bit deeper and see if I can isolate the issue some more. I'd be happy to give presonus my files so they can try to reproduce the issue.
ardware Overview:
Model Name: MacBook Pro
Model Identifier: MacBookPro14,3
Processor Name: Intel Core i7
Processor Speed: 2,9 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 8 MB
Hyper-Threading Technology: Enabled
Memory: 16 GB
Boot ROM Version: 198.71.1.0.0
SMC Version (system): 2.45f0