Sounds like you're more familiar with Premiere than AE. You need to understand that AE doesn't work anything like Premiere, nor does it behave anything like Premiere.... e.g. scrubbing in AE is the stuff of fairy tales. AE has to render EVERYTHING.
So even if you open AE in Premiere, you're still running AE, and it will still work the way it's designed to work. It's a fact of life in AE.
You might benefit from a quick tour through this:
Lrearning the concepts of how AE really works ought to be an eye-opener for you.
thanks for looking into this. Sorry if my post wasn't clear enough or the Ae scrubbing part too easy to read over.
Anyway, if I do the second set of steps (launching Ae manually before any ADL action, thus preventing Pr to launch Ae for me), I do can scrub in AE without any problems. (This is with just a comp with the source video file, not talking about super complex comps here).
This live scrubbing in Ae works for me for quite a bunch of versions down actually. Really important even for simple roto work. And kinda sad it only seems to work with mouse scrubbing.
It's not only the scrubbing though, Ae acts funny overall (panels getting slow etc).
Looks to me like an issue with memory management and or graphics card interaction with the different Ae processes + background process going on. That's why I added the 4 monitor + mercury transmit full screen playback with Ae + Pr and or the project with many dynamically linked Ae comps notes. I could very well be just wrong here of course, bugs are bugs I guess.
If you've got the time, would you mind testing it on your machine with the steps I provided?
Would be interesting to see if that is reproducible in different environments.
Sorry, I can't run a test: I work in AE/Avid. Before that, AE/FCP. I'm pretty clueless in Premiere.
I'd have to say you've been lucky so far scrubbing in AE. Most people have to RAM Preview, then scrub. Many people also prerender stablized footage to cut the processing load -- there's typically too much going on in a comp to deal with stabilization on top of everything else. Prerendering also cuts rendering and previewing time.
It sounds like there could be problems between AE-OS versions. Knowing the precise version number of both will be a big clue. Off the top of my head, I'd mention that AE CC 2014 requires Win7 Service Pack 1 to perform properly.