Thank you. This is what we ended up doing. What I was looking for was what CVARs had changed between 5.4 and 5.5 in case there was something else we needed to change.
In case anyone else comes looking for the same thing, there was nothing else different. All in all, Epic removed one of 5.4 CVAR and added 5 new ones to 5.5. The only one we needed to change in the DefaultEngine.ini was Interchange.FeatureFlags.Import.FBX=False and importing in 5.5 went back to the way it was in 5.4.