I know how frustrating it can be when FF changes your O day. Here's something that I figured out when it does happen. Go the Ovulation Detector section and click on Turning/Over Ride. Then select Fertility Awareness as your detector instead of Advanced.
That will most likely return your O day to CD19 and give you red crosshairs again. I agree, it looks like you did O on CD19 since you had a temp rise the day after, and the fact that you go a + OPK on CD18, and you tend to O 12-36 hours from the initial LH surge.
Good luck...