Just went through something kinda similar. Was trying to book an itinerary on the AC corporate rewards website.
The regular AC website would give me the itinerary but it wouldn't work on the Corp Rewards site. There was clearly a glitch which would not show business class on one of the legs and screwed up the pricing of the whole ticket.
Talked to reservations, they swore up and down it wasn't a glitch but a "fare rule" that didn't allow the itinerary (even though it allowed it on the AC site). After two hours and going through two agents and a lead that swore they and the system was right - the lead agent sheepishly came back and said they didn't understand why it wasn't working and would issue the ticket manually.
No apology, nothing - just the $5,500 ticket and itinerary I wanted to buy in the first place. I'm afraid "customer service" or ticketing system knowledge is not their forte at AC.