When placing an annotation symbol in a face-based family, it must be placed in plan view and the Maintain Annotation Orientation option must be checked for the annotation to appear in plan view when it's placed on a vertical face in a project.
However, this doesn't get reflected in the Legend Component when creating a symbols legend.
A possible solution might be to model the face-based family on the side face of the host rather than the top face. Has anyone experimented with modeling face-based families on the side face of the host? (I will post this separately too here:)https://forums.autodesk.com/t5/revit-architecture-forum/modeling-face-based-families-on-the-side-fac...