Using service factory modelling edition recently I managed to get a new service project into a position where it would not generate code with no indication as to why.  I knew it was my fault as I had deleted, moved and renamed projects a few times - it was one of those situations where I wanted to get the name right, but had an indecisive few minutes changed it, then eventually settled on the first name.  The self inflicted mess I managed to end up with was two projects in the project mapping table, and obviously by sheer luck I had chosen the one that referenced the deleted projects!

I resolves it by opening the ProjectMapping.xml and finding the ProjectMappingTable element that contained the correct projects references - basically this meant finding by project Id those projects that still exist in the solution file.