Solidworks Assemblies - Error on "Insert into Current Design"

[merten]

We are exploring a possible migration of all our CAD files from Dropbox to a Fusion Team Hub. We currently  have a mix of Solidworks and Fusion, the majority is Solidworks. Our Solidworks master assembly has 3 top level sub-assemblies with each multiple parts and other sub-assemblies. All in all over 1300 components. 

Here is what I did on my test:

Step 1:  Import of the Solidworks master assembly to our Fusion Team Hub. A simple drag-and-drop and after an hour all referenced assemblies and parts seem to be imported fine. We verify the Solidworks master assembly is viewable in the web viewer. Works. 

Step 2: Now we want to re-create the master assembly and certain sub-assemblies in Fusion. This will allow us to adjust appearance attributes for rendering and eventually link components which originate from Fusion designs with the actual Fusion sources (not the Fusion exports we had on Dropbox). Another reason for looking into the switch is to benefit from the AnyCAD reference management and the viewables on any platform/device for everyone. 

Issues:

• When performing "Insert into Current Design" with assemblies we often get errors like: Error: <___.SLDASM> cannot be inserted into <Fusion File Name> because we are currently unable to read it in Fusion. Please try again later. No details to explain the cause. 
• So if this happens, we go one level down. We create new Fusion sub-assembly files and try importing the corresponding assemblies and parts there.
• At some point it will work, sometimes only when reaching the part level all the way down. Lot's of manual effort, but at some point we want to have all assemblies in native Fusion anyways.  
• One problem right now is that when hitting a Solidworks assembly with only virtual parts (no referenced parts) it also fails, and at this point we can not go one level down and recreate a Fusion model with references parts since they are all encapsulated parts and subs in the Solidworks assembly.

Any idea how to work around the virtual parts issue? Are we doing this right? Are there any best-practices for these type of transitions?  Any help is much appreciated!

Thank you,

    Merten