Originally Posted by
hockeyguy
I'm gonna vote for MP inconsistency; I'll bet either both were or neither were but somehow just one was credited. The usual advice applies: keep trying until you get a helpful agent.
It is very possible to have a "same ticket" seemingly-return fare actually be out of a different fare bucket each way. Look at the receipt for the pricing - if they are the SAME, check the rules before you contact them again so you don't screw yourself out of earned mileage if the credited segment was in error. My hunch is that there was a different fare basis on the return (which doesn't necessarily mean it doesn't earn mileage).