Thanks you! Those changes do fix the issue.
I did note the changes in the documentation and the release notes, however, the typ byte threw me due to the bson.MarshalValue call using bson.Type and bsontype.Type being removed and now bson.Type so my brain auto converted to using the same here, which, of course, does not satisfy the interface - 
Is there a reason to not use bson.Type in this interface to keep it consistent across the two (and also the ValueUnmarshaler)?
Thank you again!!!