The plot thickens! [Linked Image]

Apparent random tripping of the GFI when different appliances are turned on usually happens when there's a neutral-to-ground fault somewhere. It trips as soon as the load is high enough for the small portion of current that's bypassing the GFI to exceed trip threshold.

But that wouldn't explain how insulating the freezer from the floor stopped the breaker from tripping, unless there was leakage from a cable neutral to the freezer casing when it was standing on the floor.