Arbitrary (?) frame count for Freeze function for Roto Brush and Refine

[Prang260142288ig2]

When I decide to Freeze the render of the Roto Brush, it sets what seems like an arbitrary limit to the number of frames it'll freeze. 

So this is the full timeline of footage that I'm trying to rotoscope out from the green screen:

You can see I have like 20-25 secs total. But it stops freezing just after maybe 8 or 9 seconds. 

Here is a screenshot of the frame count when I click Freeze:

How/why did it pick 235 frames to freeze when it should be so many more (20+ seconds worth)? 

Finding this very frustrating because it seems so arbitrary each time, and it's not consistent in terms of how many frames it caps it at. Is it a cache issue? Storage or memory issue? I think I have plenty of RAM allocated and storage right now. But curious if anyone knows. 

[Prang260142288ig2]

I've been finagling with it and i think it has something to do with how the start and end points (time ruler and/or time navigator) are set in the layer view but I haven't figured out exactly what about it. I think as long as I don't set an earlier end point, it doesn't arbitrarily cut it off (even before the earlier end point). Still testing...