Codeshare Award Help

[pilot]

I need to call on one of you guys with a solid understanding of the routing/coding involved with awards to help me out. This morning, I attempted to book a codeshare award, RT, from BZN to ORD in early July (flexible dates). There is one daily nonstop operated by UA/Ted that I have used US miles to secure several times before. The agents (tried two) both tried hard but told me that they didn't even see those flights in their system. This is *not* an issue of the award inventory not showing seats available - it is an issue of the flights themselves not even being "on the radar" as being possibilities.

This makes no sense to me because I have booked the same flights before (both BZN to ORD and BZN to DEN) and because United.com is showing the flights as not only active, but open for many seats using UA award inventory. Are there times when flight schedules are updating where they simply disappear for a bit? It wouldn't shock me if seats weren't available, but the flights not even showing up is perplexing. I am pretty sure United/Ted operates the one in question, but even when SkyWest operates some of them in the past, it didn't create a complication.

Any insight, suggestions, or answers would be greatly appreciated.