I received an error importing my profile to steam. The account is public and I can access the profile page with the test URL function on my account page.

You only need to enter your Steam username in the textbox, not the entire URL.

I'm having a similar issue, I know my profile is public and the username is correct, but the URL is failing when I test it.

I figured it out, you need to have a custom steam profile URL, otherwise the formatting will be all wrong and won't be able to find your profile.