

"Complimentary" Seat Selections
Hi everyone, I don't normally fly Air Canada so looking for an explanation.
We are flying internationally in Economy and do not have the ability to choose seat selection until check-in unless we purchase in advance. However, one leg of our trip shows the seat selection for both "preferred" and "standard" as complimentary. Upon choosing either option, though, the system wants to charge.
Does anyone know what this complimentary really means if there is still a charge? For reference, I included a screenshot of what our other legs show - the prices are clearly marked. On this leg, both show complimentary in green. This our longest flight so if there is a benefit hidden in here it would be huge.
Thanks! I have very minor status on United, which this was booked through, in case that could matter.