Apologies for cross-posting with tcp forum, but I have not yet received a reply over there so figured I'd try my luck over here.
After setting up TCP with authorize.net AIM integration successfully on a 4-site multi-site installation, something's suddenly happened and the final checkout does NOT forward to authorize.net for credit card capture and processing. The order works fine on the WP side - an email confirmation is generated - but something with the integration has gone wrong.
Note that this was working fine, however at some point I changed servers and it's possible it stopped working then.
At this point, I need some ideas for where and how to troubleshoot as there is no comprehensive information in the documentation. As far as I can see, all the authorize.net information is correct, and everything is set up correctly on my side.