I don't think I have seen LT fares on V Q S etc.

I have a current booking in Latitude to Brazil on a Worldwide Companion Pass in H class so I know they do more than Y and B! Other Latitude classes I have seen are H, M, and U but I have only ever booked one WCP, this one to Brazil in H class--no problems and instant upgrade.

This booking was made in early February of this year.

I think we would need a bit more info from tbuff before figuring out if there is a "new" problem here.

If an H, M or U LT fare is available then tbuff should be able to get that cheaper latitude fare. Maybe there are none in those classes for the LT branded fare.

As I said, I don't recall seeing anything but Y B H M or U for Latitude even though it is theoretically possible. I would like to see from EF that there is the class/brand Latitude fare available on that AC metal route on a particular set of dates.

The T&Cs are clear and supported by my and others' experience -- any econo fare on AC metal, not on a flight pass, discount etc.:

"The Companion Pass entitles a companion to accompany the primary cardholder for a fixed base fare (plus taxes, fees, charges, and surcharges), when the primary cardholder books a published economy fare on a flight marketed and operated by Air Canada, Air Canada Rouge or under the Air Canada Express brand."

"The Companion Pass is valid towards a new booking only, and not valid on existing reservations. Bookings must be made directly with Air Canada, via aircanada.com, the Air Canada Mobile App, or through the Air Canada call centre (“Air Canada Reservations”)"

"Valid for one round-trip for a companion when travelling on the same itinerary and booked at the same time as the primary cardholder."

"The Companion Pass may not be used with premium cabin fares, or in conjunction with Aeroplan flight rewards, Flight Pass, group travel bookings, Air Canada Vacations bookings, or any other discounts or promotion codes."