The nocost permission is disabled, but players are able to /up (without numbers) to metal and HQM at the cost of stones. Possibly caused by the new building skin for stones.

Using /up 1-4 says not enough resources when upgrading to metal or HQM, but /up will upgrade to all qualities at the cost of stones.

It was the Enhanced Hammer plugin causing it. Disregard. 

same without admin hammer

(20:15:43) | Calling 'Unload' on 'AdminHammer v1.13.0' took 206ms

(20:15:43) | Unloaded plugin AdminHammer v1.13.0 by mvrb