Please note. This problem occurs even when the timeline has the greenbar.
But it is worse when the greenbar is not there.
please give the exact version number with decimal accuracy.
also, just making sure - this could happen when you are doing roto with different frame rate i.e
master comp in 25fps and roto in pre-comp at 29.97 fps and vice versa.
All footage is at 24fps and nothing is precomped.
The AE version is 220.127.116.11.
It seems that the viewer behavior got worse with 2015 as all of this works in 2014.
I remember when 2015 13.7 was out, there was a similar bug where the preview would not update from time to time. if everything works fine in 2014 than I would bet it works fine also in 13.7.1 (2015 last update) and clearly this is a bug. you should tell support about it in the bug report form so all of us would benefit from a bug free Ae.
in the meantime you can use 13.7.1
It does not work in any 2015 versions. So I would have to revert to that 2014 if I can track down that install.
Thanks for your assistance,
if it doesn't work in CC 2015 13.7.1 as well, then I believe it's not a bug but something else. if you could video capture the issue or send a small collect project file, I could take a look at a small segment of the footage and see how things are looking in my system. make sure of course you have purged all memory EDIT->PURGE->ALL and also in preferences->disk cache->empty disk cache and also clean database and cache.
if you are a CC member you could easily install CC2014 through the CC APP under Previous versions. I have all the way down to CS6.