Hi Andy,

> For the SubD conversion feature is it expected behaviour that when the NURBS objected generated has a
> boolean subtraction performed on it in MOI the edges generated from that can't be filleted without errors?
> I'm trying to work out if I'm making a mistake or just expecting too much from the feature.

Well it depends on the situation. In general that is not expected, however also filleting in MoI can have problems with complex chaotic geometry and it is pretty easy to have complex chaotic geometry with SubD conversions.

Is it possible for you to post the model so I can take a look at it? If you want to keep it private you can e-mail it to me at moi@moi3d.com, if it is very large you would need to use a file sharing service like Dropbox/OneDrive/etc... and send just a shared link through e-mail.

- Michael