Oliver, thank you for the clarification. I guess I can't blame them. Availability on LH is generally pretty good.

And I did find (and ticketed) the FRA-BKK leg a few days later. Availability on that route did improve quite a bit a few days after I posted the question. I was just surprised by the large discrepancy of "any day available with M&M" vs. "nothing available in August on ANA" which I had never seen previously.