Hey Nate -
If you can dependably reproduce this, please open a case with the fine folks at Product Support. They should be able to help you figure out what's going on here.
Out of curiosity - are you seeing this across multiple workbooks, or does there seem to be only a single "weird one" that exhibits this behavior? Might be interesting to re-create what you've built in a brand new workbook and see if the same thing happens.