Which version of 5.5 are you using?
UE 5.5.4 should have the version of the library that can read v5_6 R2024 files.
If it is what you are using and it is still not working, it would be nice if you could provide a sample CAD file for us to test.
P.S. The doc page is not up to date yet, a request for update has been filled in.