I booked a flight from ZIH-SEA.

The ZIH-LAX segment arrives LAX @6:15PM. Although there were two connecting flights out of LAX to SEA offered that night they got us into SEA quite late. One of the options was to stop off in LAX and pick up a connecting flight into SEA early the next morning. I opted for that.

We used 15K to upgrade, and an agent made the deductions. When it didn't show on my itinerary after the transaction, I called back and the second agent said that because we were spending the night in LAX we could not use the same 15K upgrade for the second flight. ( Lax-Sea)

When I look at the upgrade rules it says cannot be used in "stopover".

I thought a stopover was considered 24+ hours.