I'm still confused.
I created the race in ART. I always have Use Age on Race Day set for divisions.
When I add a registrant on the morning of the event with only an age ART assigns the current date. I
If the race is on 11/06/2025 and I create a new participant who's age is 46 then ART automatically sets the date to 11/06/2025.
If I then link to RSU and sync it'll throw that error.
I don't know how RSU is determing at one point during the day the person would age up but there's some issue here. If I set the persons DOB to 1 day after the race everything is fine. If I set it to a date before 11/06/2025 it'll keep complaining. So there's clearly an easy workaround.