Xml namespaces not in model with builder

I’m trying to grab some data from within a model and output it in xml.
I’ve done this previously using the builder libs and it works a treat.

However, I’m trying to add xml with namespaces and get the following

Namespace prefix app on name is not defined

I’m trying to express the following:



name is the model and there is no reference to ‘app’ in my model. It
is needed for the destination where the xml will be used.

I’m using xml.tag! ‘app:name’ as the colon causes issues and have
tried the builder workaround for colons too with no success.

Does anyone know how I work around this?