Captcha is not working as expected.Visible on webform when logged out and invisible when logged in
That is expected behaviour. Under permissions there is an option:

Skip CAPTCHA
Users with this permission will not be offered a CAPTCHA.

Admin by default has this set meaning they won't see the Captcha. Captcha isn't necessary for an Admin since they are assumed to be trustworthy.
You can also set other roles here so that they don't see the Captcha. If you have strong Bot deterrents in user registration, you probably don't want authenticated users to have to go through the Captcha process after every node/comment/etc creation as this will just cause annoyance, especially for regular contributors. If you allow anonymous content creation, obviously you don't want to provide this option for that role, or the Bots will come knocking...