Mesh mating preview showed more face pairs for overlapped surfaces but created
MMCs are less than shown by preview.
MMC Preview shows more face pairs that include overlapped faces.
In this case the face pair shown by the Preview interests each other. You can
verify that using Analysis - FE Model Check - "Detect Interference/Clearance"
operator with value =0 (to locate any intersecting faces in the display). So
"Preview" is showing what it was supposed to. It is just a hint and not the
"Preview" does not perform the operation but gives a hint at what user may
expect. The user has to be educated about the fact that is "Preview" says a 100
faces, then the chances are high that under "normal circumstances", a 100 mmcs
would get generated but there are always exceptions.
Using a finer level of tessellation is helpful when you want to ensure that
software accurately represents the curvature of surfaces in a very thin body.
In some cases, using the standard resolution for polygon bodies on thin, curved
(though nearly flat) surfaces from different bodies can cause problems when you
try to create Mesh Mating Conditions between them.