Left image:
You select the top profile for the tangent surface fill (orange arrow), but the surface is attached to the bottom profile (black arrow).
Correction is required.
NOTE: The red section is the top of the fill surface extruding from the bottom profile through the top (blue).
Right image:
You select the top profile for the tangent surface fill (orange arrow), and click Reverse Surface.
Correction is applied.
NOTE: The tangent fill surface (green), is correctly attached to the top profile.