The root of the problem is more than likely that ANTS Load never, ever supported Ajax. The script recorder only understood x-www-urlencoded post data and not raw XML.
I have got an internal, private update I can send to version 1.75 that may or may not work, depending on your implementation of AJAX. Basically, it records the post data in raw bytes if it cannot determine the post data encoding type, which works well for generic AJAX, but makes it slightly difficult to make changes to the test script, for instance, to replace any data with State Information.
If you would like the patch, please send me an email. Note that you need ANTS Load 1.75, so you may need to update the software first.