Interesting to know now, however, I proceeded with trying to add it manually, and cannot remove, and I am getting:

There were errors when validating the App part configuration xml for part ''''/feature_ggaa6a0e-9eba-40a0-bec5-226d1db53cah.xml.config.xml''''.: Xml Validation Exception: ''''The '''''''' element is invalid - The value ''''ggaa6a0e-9eba-40a0-bec5-226d1db53cah'''' is invalid according to its datatype '''''''' - The Pattern constraint failed.'''' on line ''''1'''', position ''''171''''.

I realised I had not changed the two ID''''s in the manifest, but it seems to cache them and still not work somehow. Wondered if you had the manual steps if I missing something somewhere?