MCP2200 doesn't work everytime
Have you looked at figure 1-7: -



It may be that you need to insert a resistor as indicated - try 10 ohm to 100 ohm. Also the crystal you have linked requires 5 pF shunt capacitance. You might find that the MCP2200 has an input capacitance of 5 pF (a guess on my part) and so the actual capacitor you add at OSC1 needs to be reduced to 5 pF.