No, you should not turn off Gizmo. This plane uses SASL (instead of Gizmo), but this should not be the problem. I own many SASL-driven aircrafts and never had any problem, at all.
From my research, this plane, Cessna 208B, has not XP11 support. Without being SASL-guru, I think that runs on an older SASL version, which is not full compatible with XP11. Unfortunately, from what I am aware of, XP11 updates on Carenado fleet means to rebuy the plane at full price.