User blog comment:Xilinoc/Ch. 566 (not out yet, but dis gon b gud)/@comment-24153155-20140129222822/@comment-4484409-20140130173655

They already explained why they can't sense the Sternritter when Shuhei, Ikkaku and Yumichika met up. The Sternritter dispersed large amounts of Reishi all throughout the air disrupting the ability to sense Reiatsu...or something like that.