Sorry for the delay in getting to this. The "OK" buttons are actually iframes with a complex URL that tests various special characters. Since you had a problem with the + in URLs it's probably related to that.
If you view the HTML source and look for the first iframe element, you can see the URL and try opening that in its own URL. It may show you some error that you can resolve yourself.
But if you've fixed the problem you had with the + links, and the URLs for user pages are working fine when using that option, then it should be perfectly fine.