When I make changes to a timeline and try to generate a RAM preview, for about 80% of the time AE will throw me that error. I have to hit OK, wait a couple of seconds, then try again for it to actually render the timeline. Sometimes it won't even throw the error, but instead will just render 2 or 3 frames, stop, then start looping the playback on those frames. I have to stop it, wait, then try again. Sometimes it will even do that multiple times before I can actually render the timeline properly. It does this on simple and complex scenes alike, and I've been experiencing this all day at work for the last couple of versions.
I have 96gb of 3600mhz DDR4 RAM allocated exclusively to AE, running on Win10. I have a gen3 SSD dedicated exclusively to cached media, with plenty of headroom. The program is most certainly not starving for memory, or struggling to write those files. I have no RAM related problems on any other programs. I also have not done any sort of OC on my PC. I can only assume so far that AE is struggling to actually access the memory properly for some reason.
This is only one of the many incomprehensible bugs that have started showing up arbitrarily in AE since a couple of years ago.