awesomeminer adds a extra x16r when mining x16r , this causes the miner to fail.
this is what it looks like:
t-rex-0.6.10-win-cuda9.1_1\t-rex.exe x16r -a x16r -o stratum+tcp://X16R.eu.nicehash.com:3366 -u xxxxxxxxxxxx -p x --api-bind-http 0.0.0.0:4028
You should probably check your config. AwesomeMiner will (most likely) not do that by itself.
Check your (user) command line parametres under Online Services and also under Managed Software.
The command lines I get in AM 5.6 are:
"[...]AppData\Local\AwesomeMiner\t-rex-0.6.10-win-cuda9.1_1\t-rex.exe" -a x16r -o stratum+tcp://x16r.eu.nicehash.com:3366 -u xxxxxxxxxxxx -p x --api-bind-http 0.0.0.0:4028