Thanks for the suggestion to use "Revit Family Tools" I looked at that addin ages ago and have actually forgotten about it.
The issue is occurring when exporting the Type Catalog from the actual family! So the issue has nothing to do with the previous Type Catalogs.
The reseller is adamant that the problem lies with Autodesk. How does one contact Autodesk directly with errors? Also I really need to send the full family & Type catalog (Which is to big for this forum) then others will be able to replicate the export and import issue I am having to better understand the problem.
The problem is that there is a comma in two of the family parameter names.
Side Light Left, Transom Window Height Calc Side Light Right, Transom Window Height Calc
Because the comma is used as the column delimiter for the type catalog, Revit can't read it, and shows you the last thing it read before it encountered the error. Like "Could not parse column header: Side Light Left"
If you remove the commas from the parameter names and export the type catalog, it will work.
Do this: Open the door family. Find the above parameters. Remove the commas. Save the family. Export a new type catalog. Close the family. Go to a project and load the door family.
It works like it should. (Except if the above parameter are used in a formula, you will have to fix the formula.)
My answer: Never - ever - put a comma in a parameter name. Never. Especially if you sell your families.