Hi, try turning off Enhanced Tracking Protection for that site by clicking the shield icon at the left-hand end of the address bar - Enhanced Tracking Protection in Firefox for desktop.

If that doesn't help, disable any ad blocker you are using.

If that doesn't help, hold down the Shift key when you start Firefox to start in Safe Mode. More - Diagnose Firefox issues using Troubleshoot Mode.

If it works in Safe Mode, restart Firefox, then disable any theme or extensions you have - 3-bar menu > Add-ons > Themes/Extensions and restart Firefox again; now if it's OK, re-enable them one by one until you find the culprit. You may need to restart Firefox after enabling some extensions.

Note: If you use userChrome.css - you don't have it if you don't know what it is, this is also disabled in Safe Mode, so should be regarded as an additional suspect, and can be disabled to test by placing /* before, and */ after the file in the chrome folder, then restarting Firefox.

If your question is resolved by this or another answer, please help other users by marking the best reply as Solved. Thank you!

Thanks. No more buying at the moment but will keep this to try next time I have the problem.

Solved. The problem was with an add-on called Kopernio, an academic research tool.

Botanicalbry said

Solved. The problem was with an add-on called Kopernio, an academic research tool.

Hello Botanicalbry,

A moderator inadvertently marked your last post as Chosen Solution, while it was Scribe who suggested that an extension might be the culprit.

Would you be so kind as to rectify it ? You can do so by clicking on the "Undo" button to the right of your last post and then mark Scribe's post ("solved the problem" button to the right of his post).

Thank you in advance !

I just noticed that (either by you or a moderator) the Chosen Solution mark has been removed from your last post ....

If you'd be so kind as to mark Scribe's post as Chosen Solution ?