We have found the cause of the problem and the solution.
When we were testing we were adding the parameter as a Project Parameter associated to a category,
This works however when the family is mirrored in Revit, the mirrored elements stop showing the Enscape Proxi.
When the parameter is added in Revit Family Editor the mirrored elements work 100%.
So remember this, add the parameter to the family through the Editor and not as a project parameter.
The only problem that we have with this workflow is the insertion point/family origin and Enscape Asset Origin.
If you want this workflow to work 100% you need to make sure that the origin of the Revit family, not insertion point, is the centered with Enscape Asset.