The user loaded a blocking that was ok before and now the outer edges of one volume are blue and not white. All the outer faces of the block belonging to a single material are not projected.
The reason for the non-projected outer faces of a single volume part (here: FLUID) was a SHARED WALLS definition between that part and another part that was missing in the part list for some reason (the actual blocking might be only a sub-topology of a larger one containing the missing parts or another tetin without the missing parts was loaded). Also the part for the shared-wall-surface elements is missing. Missing parts are replaced by the default family ORFN. Hence, the shared wall definition in the blocking file looked like
ORFN FLUID ORFN
which caused the non-projected outer faces of the FLUID-blocks.
Editing the blocking file and deleting the ORFN FLUID ORFN enty fixed the issue.