Massive Net mature negative

[clearlyqt]

I wasnt feeling well enough to read for a day so decided to do a cram deck on a bunch of cards, with the setting set to not change any scheduling, just a review refresher and send them back into the deck they came from, for some reason after they sent back the net mature graph looks like this, any way to fix it or know why this happened, the strange thing is also that the cram deck was about 2500cards with over 90% being correct and sent back to the deck immediately, so this number is very strange as it seems only part of the deck was classed as lost and was greater than the actual fails, even with it set to not change anything.