How many actual streams are you testing with, just 2? If 2, I'd suggest trying like 10 and see what the results are. BTW, AE/LAG/PortChannel does not load-balance, they load-share. Generally with enough streams/traffic the load-share comes close to 50/50 load balance, but never a requirement. For true load-balance you need to switch at a packet/frame level (not session) which could lead to potential for out of order packets, which creates worse issues than non-load balance.
If with 10 you still get same results (all hashed to 1 link egress from EX2200) then I would suggest you open a TAC case and see if there is any 'hidden' way to change the hash algorthm.
Good luck.