Never mind, found the problem.
The comment is at the type from which the variable is created, but not at the variable directly. Now I need to find a way to access that type comment somehow from my VariableDrop^^
Comments are primarily for the PLC code, so they are not inherited from the type definition because the element of the struct instance does not appear in the declaration PLC code, anyway.
If you want the text to be available at all instances of a structure, you can use the Label property. If no comment is specified, the VariableDrop.Comment property returns the Label as fallback.