In order to help you best, I will need some more information about your testing scenario:
1) Could you please describe us better your testing goal and what kind of element you are testing?
2) If it is possible grant us access to your application (or a stripped-down version) so we can reproduce the issue on our end and give you a solution.
If direct access is not possible, capture a Fiddler trace and attach it to this support ticket in a zip file. If you are unfamiliar with how to do so, this link
will provide you with step-by-step instructions for download and use. If taking a Fiddler trace please be sure to:
1. Click Clear Cache first
2. Check Store binaries
3. Check Decrypt HTTPS traffic
Hope to hear from you soon.