[MikeReganNoise]

Right, I don't have evidence of a 3.2 MB limit. In my case, the session got to 4MB and then the corrupted backups that followed were at 2.6MB.

Here's the only thing I could otherwise consider as a consistency. Mac OSX 10.12.6 as the OS and PT Ultimate 2018.x as the originating version used to build/prep the session. Like I said in my post, the template I used originated in the UK and the jobs were prepped (one was an OMF the other an AAF) in 2018.4 (originally, I was incorrect in stating 2018.10) I brought one of these jobs home to my rig and opened it with 2019.6, then worked a couple of days, and then for some reason after the last day of working encountered the issue. I rebuilt the corrupted session in a different template, have returned to the same spot to continue work and have not seen the issue yet. But I'm not at all confident it won't happen again.