Ok on trying to make progress I have accepted the problem in the 2nd map and tried to proceed through the 3rd map file. This has died at a similar point. The stream position is less than the total length but the last xml element has been processed and the xml location is back at the base Asset point so end of file. The content.load process continues and loads what should be a encoded int of a data type but ends up with something not recognised as its out of the range of the types list it has loaded for this process.
I am now suspecting that the xnb file is not formed correctly.
As all my problems seem to be coming from the pipeline and its handling of Xml I am wondering if I am a rare user of this part of MonoGame and so these sort of problem have not been seen before.
I don't mind continuing but don't want to waste the effort if its just for me.
So my question is now:
Does anyone use MonoGame for Xml processing or not?
I will hold until I get a response or my other work dries up and this becomes my only stuff to do.