I assume you already tried making an exception for the site in Adblock Plus... since the problem relates to ads...

Did this feature ever work in Firefox? If so, you could try clearing your Firefox cache and your saved cookies for the site. (Steps for that are listed below.)

If that button never worked in Firefox, have you considered possible interference by add-ons? You could test whether Firefox can work with the site when your extensions are deactivated by opening the site in Firefox's Safe Mode. (Steps for that are listed below.)

When you have a problem with one particular site, a good "first thing to try" is clearing your Firefox cache and deleting your saved cookies for the site.

(1) Bypass Firefox's Cache

Use Ctrl+Shift+r to reload the page fresh from the server.

Alternately, you also can clear Firefox's cache completely using:

orange Firefox button (or Tools menu) > Options > Advanced

On the Network mini-tab > Cached Web Content : "Clear Now"

If you have a large hard drive, this might take a few minutes.

(2) Remove the site's cookies (save any pending work first). While viewing a page on the site:

• right-click and choose View Page Info > Security > "View Cookies"
• Alt+t (open the classic Tools menu) > Page Info > Security > "View Cookies"

In the dialog that opens, you can remove the site's cookies individually.

Then try reloading the page. Does that help?

Trying Firefox's Safe Mode is a standard diagnostic technique to bypass interference by extensions (and some custom settings). More info: Diagnose Firefox issues using Troubleshoot Mode.

You can restart Firefox in Safe Mode using

Help > Restart with Add-ons Disabled

In the dialog, click "Start in Safe Mode" (not Reset)

Any difference?

I noticed someone else posted this same problem in December, but didn't report back on whether the suggestions there were helpful. I have try to load photos on advert on gumtree website I can post advert but will not let me load photos on advert. Please let us know whether any of the above is useful.