Assuming you're not logged in as an elite and it was saverpass you just need to call again.
Laav davke my friend, I believe that besides the fact that every airline allows some more space for their own kind of miles, that there are 2 types of star alliance partners (at least).
Say, where air canada finds availability (on say LH) CO or BMI might not find it.
US has a longer delay till seats reopen compared to ana, and so on.
Just things you notice along the way.
You might find different theories to what I said, but those things happened.