SRAM X01 Eagle (12speed) in 11speed transmission: it work?
To quote Art's Cyclery:

"Eagle drivetrains are not backwards compatible in any way (the exception being SRAM’s direct mount cranksets, which will still require a new Eagle chainring)"

and VitalMTB:

"SRAM will only make the Eagle chainring in the direct-mount style at first, and we were told it's the only Eagle component compatible with their 1x11 drivetrains. No 11-speed products will work on Eagle."