Hey FLRB, I had similar problems with the first chainset I planned to use (SRAMX9 on 2×10). Same issue with Knards and Chronicles. Switched to an old 2×10 SLX and bash and same problem. Pondered 1×10 with extender cog but with the hills round me just didn’t seem viable so opted for a new 2×10 SLX which with Knards is fine in all gears on big ring and fine in all except largest rear cog in small ring when it buzzes the tyre. Rotating the BB backwards so the crank axle was at 9 o’clock helped.
I can get by with this and think I may get all gears with Chronicle fitted as at a glance when I tried them both a while back the Chronicle was a wee bit smaller.
Thought about edging BB out a few mm, but that seemed like an unattractive solution. I’ve never used the smallest cog at the back so I’m thinking about using that as a spacer behind the big cop on the cassette to step all the gears over one if I get to the stage where I really need that bottom gear. Not sure if this would work and doesn’t sound like it would solve your problem completely – maybe 2×11 is just a cog too far…
NM – that’s odd, I have always found Sam really responsive. Are your calls and emails all recent or over an extended period? Maybe he was just out of office last week. Anyway he keeps an eye on these threads so I would expect he will get in touch with you directly after your post.