2017.08 cuts out on VST's

I just rolled back to 2017.07 because the new version was causing my plug-ins to cut out after so many seconds as if they were in demo mode.  I noticed this with TH3 and Wave's Codex.  Superior Drummer seems to be unaffected by this, maybe because it's not sustained notes.  After rolling back, those plug-ins worked flawlessly.  Has anyone else seen this behavior?  I'm just wondering if I missed some setting or another, of if this is a possible bug.  Otherwise, I'm a happy camper.

I have Codex loaded for several days, I dont have any tracks with it yet, but it did not become a demo. 

I think what Lynn meant by "demo mode" is that audio was cutting out, as some plugins do in demo mode.
 
My current project is all-MIDI, with 5 instances of Kontakt and 9 instruments, plus Trillian and Superior Drummer, for a total of 11 unrendered virtual instruments. It's pretty demanding on both CPU and I/O, but I haven't had any dropouts. Does that prove anything? Nope. Only that whatever your problem is, it's not universal.

I use a buffer size of 256 when recording and 1024 when mixing.  Again, all is well in 2017.07, but not so in 2017.08.  Just curious, how do you maintain your timing with a high latency when recording keys or programming drums manually?