Did you check the $LatestError variable?
The latest http response shows the response as received before parsing.
The error is:
Attribute 'SD_SOFM_SRV.SalesOrderQuery.meta_objectURI' has a maximum length of 512, tried setting a value of length 629.
Is this something I can configure?
Ross
EDIT: Turns out you can and it's easy. Thanks for steering me in the right direction.