Well if you want to Race you have to Advance to next session, what I said was
"Don't ever click "Finish Session"", if you do that before the Time runs out or there's Laps to be completed it messes with the AI. Once the Session has ended normally THEN you can advance to Next Session.
Regardless have you done what I advised re the player.json? This is the important bit and if it does help
please send me the json file which you had issues with.
FYI I did a race yesterday; Qualifying ended Wet, I started the Race Wet and when it began to dry the dry line appeared and the AI pitted for slicks. All worked just fine (GT3 @ Silverstone GP) and they only came into the Pits that once.