Yes, you are right, sorry about that.
I tried this in SITL, and indeed when setting circle bitmask 0 disables the tin can fence centered at home too. It was also in docs, I missed it.
Note
Polygon fence type includes the circular fences specified in the Inclusion/Exclusion fence list. The simple home centered CIRCLE fence is a separate fence. Rover ignores altitudes, if set.
Sorry for the misleading information before.