LTC1668 - COMP1 & COMP2
Date sheet says: -


  The COMP2 pin ties to a node in the output current switching
  circuitry, and it requires a 0.1 μF bypass capacitor. It should be
  bypassed to VSS along  with  COMP1.


There is no justification to expect that it will function with optimum performance if this rule is ignored. I'm not saying that there are exceptions but those exceptions are not listed.