Unable to que with a friend in flex que

Hello, for the past two patches I haven't been able to que with my friend Riocanth in flex que, me and my friends did a bit of testing and it seems he is the ONLY person I am "ineligible" to que up with in flex. I don't understand why this would be because at the end of last season as well as in preseason he ended in plat 3 flex and I ended in gold 1 or 2 flex, and it will not allow us to que in the beginning of this season here in placements (We have not finished placements yet so i still don't know if we will be able to que after them or not). Please help!

-Thanks