Don't fret it, FF will make guesses at times that are wrong, those dotted lines means it's unsure! FF has given me dotted crosshairs twice this month already, and then removed them again as more data came in to say otherwise. Lol.
Just keep bd keep plugging the data in, and hopefully you'll get a good solid temp shift after an obvious O and FF wil give solid crosshairs. Keep going!
Also, my temps are always up and down, and they always look shocking and unreadable until there is THEN a shift upwards properly and it becomes more obvious. Check out my chart today, and I'm 99% confident I'm Oing today, so let's see what my temp does in the next few days!