I get a system freeze/beach ball too, mostly during ram preview. Same OS version, same AE version, i7 iMac, 20gb ram.
Also, I have auto save enabled but it doesn't appear to do it. I don't get a folder with the saved docs though it's enabled.
Things have been stable for a long time, this is frustrating. Any ideas welcome.
After effects has become effectively unusable until I can fix this...
Ok I turned auto save off and then on, quit and restarted and auto save appears to be back. I still get hangs trying to preview though.
I'm still getting this bug, even after re-installing After Effects. Auto save seems to be triggered after a long Warp Stabilisation analysis process, when stabilising starts, the autosave window appears and then After Effects is completely frozen until I force quit. This is even after autosave has been disabled in preferences. I'm at a loss as to why it is happening, I've reverted to processing larger files on my laptop, which so far hasn't had the issue.