Reissues/exchanges not allowed to EOU/ERU fare types

We booked a round-trip flight through Chase Ultimate Rewards (credit card rewards program and travel agency). We are currently on the trip and have to change the flight back to a future date. The main carrier is American Airlines but one of the flights is carried by Alitalia.
An agent / customer service representative told me that we can't change our ticket after departure (from home) due the following part in the fare rules:
**REISSUES/EXCHANGES NOT ALLOWED TO EOU/ERU FARE TYPES. AFTER DEPARTURE CHARGE USD 275.00/CAD 275.00.*
Does is make any sense? I understand there would be an additional fee but the agent said it won't be possible to change the ticket at all.
For the complete fare rules see here: https://pastebin.com/LuzR0VCm
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What is the difference between basic economy and main cabin on American Airlines?
The main difference between main cabin and basic economy is cost. For cheaper airfare and more money in your pocket, you trade flexibility for flight changes and/or cancellations, seat selection options and the ability to earn miles at a high rate. Love them or hate them, basic economy fares are here to stay.What is class O on American Airlines?
AA fare codes for economy class in this order: Y, B, H, K, M, V, Q, S, N, L, O. Fare codes sorted by type: Coach excursion fares are: B, H, K, M, V, N, L, Q. Employees: E. Government: Y/L.How do you pull up fare rules in Amadeus?
To view fare rules you can use FQD for example :What does economy l mean on American Airlines?
Basic Economy is the cheapest fare class onboard American Airlines \u2014 a no-frills experience that includes some standard onboard amenities, but with many restrictions that will tempt plenty of flyers to avoid this option.AMADEUS TICKET CHANGER REISSUE FOR UNUSED TICKET WITH NO ADDITIONAL COLLECTION
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