CreateNewOverrideCompletionData does not get called

[mhw3l]

Hello,

I implemented the "ICompletionDataFactory" interface to realize IntelliSense-features in my projects. But I get wrong completion data for overridable method names. I noticed that the method "CreateNewOverrideCompletionData" only gets called when the input string is something like

public override $

(without a type!) where $ is the cursor position.
But when the input string is something like

public override string $

(which is more correct) then "CreateNewOverrideCompletionData" is NOT called. Instead I get completion data containing all kinds of types but not a single overridable method name.