When importing a Solidworks 2018 CAD assembly, if the part in the assembly is a virtual part (denoted by brackets in the feature tree), a part that exists only within the assembly, the part and related sub-assemblies (if any) do not appear when the assembly is imported.
This issue is in 4.19.2 (0.182) and 4.20 (4.20E2)
Results: The Virtual parts aren't imported
Expected: Virtual parts are imported
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-63230 in the post.