Actually, it looks like LX is 'playing' with availability, based on the POS/M&M account country (
http://Help.KVSTool.com/#Factors).
G_G &
IMH: Where are your respective M&M accounts based?
This looks like the explanation.
My M&M account is registered to my US address, but when I found availability at
miles-and-more.com earlier I had logged in under Germany/German.
Checking again, without clearing any cookies: if I log in as USA/English I cannot see availability. A minute later, logged back in as Germany/German, I can... No idea, of course, what would happen if I actually wanted to book this.