Be aware that FME does not support 100% of all the object types that can occur in a dgn, that goes in particular for 3D objects. Examples of dgn objects that cannot be handled by FME include point strings (type 22) and certain types of 3D solids and 3D surfaces.

Have a look at this page: https://docs.safe.com/fme/html/FME_Desktop_Documentation/FME_ReadersWriters/igds/Feature_Representation.htm

If you compare this list with the Bentley documentation (https://communities.bentley.com/products/microstation/w/microstation__wiki/8855/element-numbers-and-types), you will notice that some IGDS element types simply aren't mentioned in the FME documentation, and therefore aren't supported by FME.

Take a close look at the FME log for hints or warnings about ignored objects.

Thanks very much for your response David. I will look into it

@wheeler1​ : Did you ever get an answer to this? Looks like I have a very similar problem of curved surfaces in a DGN not getting read properly.

Try again using FME 2023.2 (available as beta, will be released in a week from now) or later, it seems the geometry support for 3D DGN objects has been extended.

I have tried FME 2023.2, and whilst it is better than 2023.1, it still skips certain features or only shows the linear structure rather than the curved solids.

(Also the translation log of the DGN reader shows many messages about AutoCAD and DWG. I didn't know these two formats were related)