AJAX Username Checker returns "No Indication"

My site's registration form uses AJAX Username Checker, which works correctly, unless a user picks a username that's already taken, attempts to register anyway, and then tries to change the username after being returned to the registration form. When a user puts in a new username, AJAX Username Checker will return the message, "No Indication" instead of the normal, "The username, '[USERNAME]' is free for registration: you can proceed."

Disabling SEF, unpublishing all modules assigned to the registration form's menu item, and changing the menu item from the default template to another did not solve the problem.

I am using CB 1.9, CB Conditional 1.9.0, and CBSubs 3.0 GPL on a Joomla 2.5.9 site. Validation is enabled in CB Conditional's configuration.

What would you suggest doing to help diagnose and solve this problem, or at least find a good workaround?

So it only does this after a failed registration attempt? Normal registration attempts it's working fine? The language string for that message is _UE_NO_INDICATION and looks like a normal response in comprofiler.php of tabClass function, but don't see why in this very specific scenario it'd display.

Yes, this error only shows up after a failed registration attempt.

I used Debug Mode, set error reporting to "Maximum" and set "Debug Language" to "Yes." I found that there was a parsing error in one of my language files, which I resolved by deleting some old extensions, but that didn't fix the original issue.

I also disabled the component CiviCRM, which had been the cause for some unrelated PHP warnings. However, that didn't stop the problem either. Unpublishing CB Conditional didn't help.

Is there a possibility some other extension or CB plugin could be causing CB to have this problem, or does this sound more like an internal issue (I'm personally leaning toward the latter)?

Has anyone out there been able to replicate this, or is having the same problem?

Have tested 4 different installs and could not confirm your issue. Do you have any caching enabled? If so try disabling all caching and purging any existing cache.

Caching has been disabled the entire time, and I double-checked to make sure that it was. I also purged the cache, and the error persists.

Strange, please PM backend super administrator login credentials and will take a look.