I just found that there is an issue regarding the importation of .STEP files in Shaper module, here there is a step model of two cubes one next to another in one step file Part Studio 2.step (16,6 KB)
if we import it in geometry module (using file/import/step), it will be imported as a compound that when exploded into solids, we recover correctly the two cubes that make the geometry.
if we import it in shaper module (using file/import/from CAD format), it will import only one of the cubes, and when inspected it says that it is a compound consisting of 0 shells, 6 faces and 12 edges (so really a cube…) nevertheless it is not a solid, and if instead we import a step file of only one cube (following the same importation method) it imports correctly a solid consisting of 1 solid, 1 shell, 6 faces and 12 edges. (here is a step file containing only one of the cubes of the first step file Part Studio 2 - Part 3.step (8,8 KB))
this was done in salome 9.9 in windows
issue was reproduced and escalated to core developers - thanks