I can't see your chart as I think you've linked to your home page and it's asking for a log in, you need to find the one that you can share (sorry it's been a while since I've used FF and can't remember exactly).

If FF is showing a dotted crossed lines then it means it hasn't made a firm decision on when you O'd and is waiting for more information before it does from memory. ie a more definite thermal shift possibly.

My feeling is to go on your own instinct too BTW. Use it as a guide but not as gospel.