There is definitely something that broke the XML Engine here. Even when editing the XML directly I am not able to do any changes at all and VERY VERY weird things are happening. I tried another computer and different browsers and still have the issues.
Some of the issues to note:
– When I manually add a line i get the XML section character which should not be there.
– When I save a manually typed line it breaks the page
– When copying something and pasting it pastes it twice!
– When you remove the line manually added and save the page works again!
– This behavior is only for this page, other pages do not have this issue.
– I tried multiple browsers and PCs. I mainly use Chrome and never had this issue until now.
–I tried numerous different fields
–To be exact I have 20540 lines in the XML.
PICS below: 
