preferredPayloadType not honored

I am working on connecting generic webrtc client with mediasoup backend, it works in my prototypes, but i want to reduce number of transports to one and i hit a wall - preferredPayloadType is not honored by consumers. Tried to search the code - it looks like it is not used on native side at all. Am i missing something? Is there a way to force use specific payload type instead of generated one?