Force capitalization in iOS web page?

This should be easy to fix, but I can't find out why it's not working.

I have a web "app" that runs in Safari, and it's made for users to add to the home screen. There's a web form where the user enters a first and last name. Here's the simple code for that form.

        <fieldset>
            <div class="row">
                <label>First Name</label>
                <input type="text" name="first_name" id="pFirstName" value="" autocapitalize="on" autocorrect="off" placeholder="John" />
            </div>
            <div class="row">
                <label>Last Name</label>
                <input type="text" name="last_name" id="pLastName" value="" autocorrect="off" autocapitalize="on" placeholder="Doe" />
            </div>
        </fieldset>

Very simple. The problem is that the Last Name form is not capitalized when the user switches to it. I ran it directly in mobile Safari, and it worked fine. When I added to the home screen, I had the same issue...

Is this just a bug in iOS/webkit (because it used to work...)? Not sure if there's some sort of script to force the auto-capitalization? Thanks!

Edit: If I click on the field directly, it capitalizes. The problem is when I fill in text for first name, and click the "Next" arrow on the top of the keyboard.