Hi there @Planker81,
Going back a fair way, but I used to encounter this also.....I believe there was a precision setting somewhere in Rhino that fixed it.
If you are still unable to get it working, maybe post an offending instance of the STEP file here for further interrogation.
Design Manager Streetscape Ltd
Solid Edge ST10 [MP2] Classic [x2 seats]
Windows 10 - Quadro P2000