Upfront not loading, "another tab is already working on this"

Hi,

I cannot load a page with Upfront. Developing on localhost. I created the page and have been working on the page and site for 2 days. Now it just keeps saying "another tab is already working on this" which is incorrect. This is the ONLY page open. I can't get past this notice to edit it. What on earth do I do? I've literally been waiting for an hour!!

Also, how do I change the background colour in the default Contact form when active? So, this is not Contact Form 7 but the default Upfront one, not when I hover over it, but when I start to write in it.

Thank you.

Robin