[*]Has anybody seen any other flights besides UA4985 with this behavior?
Yes, a bunch of United Express flights have this missing-inventory situation. See
http://www.flyertalk.com/forum/unite...ghts-only.html .
[*]Is it worth pinging somebody (maybe UA Insider)? I'd sorta like to get an award seat on this flight...
If you're willing to pay for a standard award, you should be able to phone it in per reports in
http://www.flyertalk.com/forum/unite...ghts-only.html and as long as there's at least one seat for sale and you're a UA elite member you should get the standard "last seat for elites" inventory.
Otherwise, if the flight is X0, I haven't seen any reports of people finding magical XN on these flights that have no XN buckets published.
That being said, if you're booking a longer journey that needs this segment as a connection, sometimes UA reservations can help force open the inventory on the little flight — it's worth asking nicely.