Well those are all the normal ways it’s supposed to behave- using in and out points to determine length of final render, or use comp length.
But for some reason it seems to choose a random In point that is not the in point I have set nor is it the beginning of my comp and that is what is so weird.
The one thing I suspect is that it (for whatever reason I don’t know) seems to choose the placement of my cursor on the timeline as the place where it chooses the In point.
But I still don’t know why.
Using:
After Effects CS 5.5 running Lion on a 2009 Mac Pro.