Excel Roundtrip: Error to Update

Problem: Content Items couldn't be updated with Layer. 

1. Search for the ones that weren't updated to validate what went wrong. 

   1. How to find items where the field is empty.  

2. Conclusion: These are the 5 Virtual Items to which I cannot apply the Layer. This is a layer setting which is called "Available for", which prevents the layer from being assigned to Virtual Items.