That was one of the solutions I tried as well - it is really starting to seem like it is validated somewhere deep, deep in the source code(or maybe I`m too much of a novice to find it).
Weird thing is that classical entity(just a string value replacement):
<!DOCTYPE replacements [
<!ENTITY replacement "Replaced value gets through">
]>
<foo>&replacement;</foo>
gets through and is present in the response as opposed to any other variation of XXE(xml bomb, replacements with results from FTP/HTTP/FILE links).
Anyways I think I`ll have to move away from SOAP UI for my XXE demo - really wanted to utilize it, I am a fan of the product.
I still appreciate you trying to help nmrao! Have a nice day!