I've never had any issues with AV, though they seem to not release much space to their North American flights I feel like, and almost nothing to EZE, but that seems to not just be them, had the same issue looking at LATAM.
Copa has been an issue forever now, it's really bogus since AV doesn't have great space to some places, CM would be the backup plan. Was trying to book a multi city, YVR-EZE-MSY-YVR. It's available, but the only routing I was given (since it's more than 330 out) was YVR-YYZ-EZE-YYZ-MSY-YYZ-YVR, which obviously isn't bookable cuz you can't transit the same city twice. Brilliant. This thing has to get fixed.
I'm ok with them blocking CA awards. They've had way too many people show up to CA flights and be told "you don't have a ticket" apparently. So until that's sorted out, I'd rather not have those situations happen to me or anyone else. I wanna fly CA, but I don't wanna get stuck. Maybe I'll use SQ points for a CA flight, but who knows.
LX disappeared for like a week there, a week where I was furiously trying to book an award. Sure enough like the day after I book, it's back lol. At least it was resolved quickly.