Autocase correcting not working as expected

I've got Document.AutoCaseCorrectEnabled = True, but it only seems to work on language keywords and primitive types. I.e.

dim v as double

if correctly converted into

 Dim v As Double

but

Dim p As point3d

is not converted into

Dim p As Point3d

even though the custom type starts with upper case P. The autocomplete list for p. lists all Point3d members so the editor is clearly aware of the type and know p is of type Point3d. What do I need to do to fix these capitalization errors?