Yes it was. It turned out to be a dynamically generated ID is the iframe elemen. Here's a copy of that response:
Thanks for posting the error and screenshots. The error message "Unable to find target host" means that for some reason the frame is not being found. When you're testing elements inside of a frame there is an URL which is used to connect to the frame. Please make sure the URL is correct.
Another reason for this error could be a dynamically generated ID "DlgFramef1b84c1a-3014-4e8e-a218-66dfb8c34931
" you can try using this expression instead "~DlgFrame" in the ID field, as shown on the screenshot.
If this doesn't help, the best and the fastest way to troubleshoot this, is to reproduce the issue locally. Is remote access to your site possible? If it is not possible, perhaps you can point us to a public site that demonstrates the issue.
Hope to hear from you soon!
the Telerik team