If you are just using a straight USB C dock, not one that requires the hybrid connector, then the problem is likely that you have the wrong cable.
Unfortunately, USB-C cables are _not_ interchangable, and unlike USB 3.0+ type-A cables, they are not typically externally marked.
The basic USB-C cable is USB 2.0 only and can support up to 3 amps at 20 volts. All USB type C to type C cables must be able to handle this. Anything cable that exceeds that needs a electronic ID chip in the cable to tell the host what the cable capabilities are. This includes USB 3.x superspeed (with 1 or 2 lanes at 5 or 10 Gb/s each), alternate modes like thunderbolt, and 5 amp/100W charging capacity.
Many docking stations have captive cables to get around this problem. Alternately cables confirming to and marked as thunderbolt should usually work.