According to posts here and elsewhere, United phone agents see the exact same thing on their internal system that customers see on their public-facing website -- that is, nothing. Award inventory for all the mentioned carriers simply does not appear in their systems (because United is explicitly and intentionally blocking all of it).

I would say that building a system where it's an option to intentionally block all award availability on partner airlines is pretty consumer-hostile, and when United encounters some undesired glitches with award inventory (which was their original explanation for blocking all award inventory on all these airlines, back in December), the first action they take is to flip the "block everything" switch, then they quietly sit on it for weeks without owning up to what they did, reveals a lot about United's inclinations and their attitude towards members of their loyalty program. It sure makes United look like they don't give a damn about their customers.

Of course, letting it just sit like that for now nearly 2 months only reinforces that image of United as a company that treats its customers with contempt. Not quite the same as viral video of a bloody passenger being dragged off a plane, but a lot of people have had their travel and family holiday plans completely disrupted because of this, and it's pretty obvious to anyone who's paying attention that this just is not a priority for UA.