Design model has been attached in sheet model as self attachment in either a DGN or DWG file. However, when changing lineweight values or even turning on lineweights in the model they do not appear in the sheet or drawing model.
Open sheet model
This value can be changed to “From Parent" to inherit view attributes from the design model
As seen above this can affect other view attributes settings for reference files which can can be separate from the master file.
The comment about DWG support isn't quite true. DWG has a Viewport Override which allows, similarly to Level Overrides in the above scenario, the ability to have separate settings between model and layout.