There is an issue I've observed for a couple of years where TK award inventory doesn't show up on partner airlines for an entire month for random routes even though TK themselves has plenty of availability. I surmise it's an IT issue because it's always for exactly a month and it's for random routes which wouldn't make sense for a general blackout/seat block, for example all IAD-IST flights are blocked but not JFK-IST flights. It's always precise by the month, i.e. lots of seats every day the previous month until the last day, then not a single seat on that route any day in the "missing" month, then plenty of seats the next month.
I made a decent effort to find someone at United or TK to talk to about this, but they have their IT teams sequestered well and it's much easier for them to simply say there are no seats available rather than spend any time investigating the problem. Hopefully at some point in the next decade they upgrade whatever system has a bug for some other reason and it fixes it, but not holding my breath.