Window Family not showing mullions correctly

[oliviaVY7XE]

I built a window family in revit and in 3D the mullion shows up, but in 2D, north elevation the mullion doesn't show up. If I flip the family, it shows up but not the exterior trim, so it doesn't really work that way. 

[ToanDN]

Flex the wall thickness in the family and see if the mullions are correctly constrained to the window plane.  If not, then restrain them.

[barthbradley]

Change your View Detail Level.  

[barthbradley]

Change Mullion's Visibility Setting in Mullion Family. Right now, it isn't visible in Left/Right Views. Note Detail Level Visibility Settings as well.  

 

My recommendation is to check every box under Visibility Settings, load Mullion Family into Host Family and control the Visibility Settings of the placed Instances through the Host.  FWIW.