Limit to Formatted Member Sets?

Gurus,

I am working on an input schedule that needs to utilize a formatted member set (repeat block) of 20 rows. When I use the full block, BPC leaves a few of the last rows out of the expansion. I've found that if I condense the repeat block to 13 rows, it works fine. Is this anything you've seen before? If so, what am I doing wrong? Is there a workaround? I am working with 7.5MS.

Thanks,

Matt