Yes, it’s usually a case of HUCA. I had it in writing that I “could contact AY for a rebooking at a later time, closer to departure”.
Yet the agent said it was debatable of “less than 72 hours before departure was acceptable” and lots of such bull. In the end (after quoting me a fare difference), he offered to remove the flights from my ticket (so it wouldn’t be a no-show), check with HQ and get back to me. But this was ONLY because I had everything in writing. In any case it wouldn’t be possible to rebook beyond September 2021.
The next day, I simply tried the chat again and the agent rebooked me for free for October 2021 (unfortunately changing my D ticket back to I class). In the evening, I also got an email from the first agent where he said HQ had given him a green light for a rebooking.
Always keep records...