I am flying J in Dec from LHR - MEL and the seat assignments just opened up.
I rang and requested 86A on the 747 leg of the journey.
I was told that they don't assign exit row seats until check-in.

This was odd as I am flying LHR-ADL this week and have had 86K assigned to me for several weeks, outbound and inbound.

Was the agent just spinning me a line? Should I request again in HKG when on my way through this week?

Can anyone shed some light?

I am OW Emerald with AA, if that makes any difference.