Firstly, what do you expect, they don't call them "Fowlups" for nothing?
That said, I can't find it on Suttons online microfiche either, so in this case it's probably Yamaha being unhelpful.
As I believe Fowlups are also a KTM franchise, go back and tell them you want the following KTM part.
54613205000
REPAIR KIT 28MM
Should be about �8. Same Brembo caliper used on most KTMs as on the Tenere.