I've checked the meesages and there is a different user agent doing the work within Acrobat.
Designer WSDL based queries use
User-Agent: Mozilla/3.0 (compatible; Spider 1.0; Windows)
SOAP.invoke methods uses
User-Agent: Mozilla/3.0 (compatible; Acrobat Annots 10.1.1 )
Could this be causing the proxy issue?