Correct, the debugs clearly show the traffic is permitted and assigned to the same flow.
One thing I notice is that there seems to be a lot of fragmentation on the flow. Can you confirm the MTU settings end to end are all matching (if you haven't already).
If that checks out you could try lowering the mss to 1350. I have occasionally seen problems with some ISP where lowering mss prevents packet loss on flows particularly when fragmentation is a factor.