Auto-fill is broken

Multiple times I have joined a match where I put adc/mid as my roles, but I've been autofilled to jungle/top/support, and yet the person who was put into adc was autofilled there from the primary that they had selected. Seems like if I have adc as my primary, I shouldn't get filled to the role they have as primary, and vice versa. Not really sure how to describe the issue better than that.