I have a an unmanaged solution "My Solution".
It contains the Account entity, and the card form "Account Card form". And many other things.
When I export that solution from CRM (normal click "Export" in the UI), the form is not actually contained in the zip and its customizations XML. It is listed as a root component... but the form is not present.
Why is this happening? This is preventing me from deploying any changes to this form. (if there were any, I'm not positive, but others are working in here and its very possible they made changes - so I'd like to grab everything to be safe)
Looks like this is what's going on...
As a test, I modified the form. THEN when I exported the solution, the form was included like I originally expected.
It seems if a form is managed/OOTB and hasn't been modified, it will not be included in the export.