I thought it was long image sequences, but build 60 crashes whenever I try to preview any art after adding to even a brand new project.
Launch, Import Files (anything I've tried), double click the art or add it to a new comp and double click the comp to see what's in it - boom, crash.
I've tried deleting prefs, I've tried uninstall/re-install, I've tried uninstall/delete everything AE I can find or think of, nothing's worked. This build seems cursed on my machines (10 core 2020 iMac running 10.15.7 and an i7/1080ti Windows 10 box fully updated).
SOOOOO....I got mad and uninstalled everything Adobe on my machine, re-installed just After Effects, and then the beta, and now it works. So likely the beta installer screwed up something somehow. Hey Adobe - please fix. This took me hours to untangle, when it should have been a smooth update as usual.
Moved to the After Effects Beta forum.