First, they will only react with other objects that are dynamic.
Second, If you want the objects to move freely with physics then use a rigid or soft body tag instead of collider (think of a collider as floor or wall or rigid body that moves with a parent object.
Also, there is a chance the normals of the imported OBJ's are inverted. I'd actually check on that first with any OBJ imports from CAD software.
To check if the normals need correction:
Make sure you have normals display turned on: viewport menu > Options > Configure... > Display tab , Polygon Normals.
Select all the polygons and and make sure they are all the same shade (blue or orange I believe). If they are blue and the numerals are facing inward then right click in the viewport and select "reverse normals". If they are random with some facing inward and some outward, the first right-click in the viewport and select align normals, then reverse normals.