Use a KMC X10 SL chain on an 11 Speed cassette?
They will not work at all. Use an 11-speed chain. 

If you use the 10spd chain, there is a good chance that it can:


Jam in the rear derailleur jockey wheels
Increase the friction on the cassette, which will:
Increase wear on the chain's side plates, dramatically increasing the chances that the chain will break right in the middle of you hammering up a hill.
It will also shift quite poorly.