Problem with Firefox & Vanguard login page

[Mr Pointy]

For the past few weeks I've had a problem with the Vanguard login page located here:
https://secure.vanguardinvestor.co.uk/Login

In Firefox it doesn't render correctly or completely:



The ordinary Vanguard site works fine but as soon as I go to the login page it fails, even with all add-ons like NoScript, Ublock Origin & Privacy Badger turned off & cookies cleared. It works fine in Vivaldi & Brave.

Any one have any ideas how I can resolve this?

Edited by Mr Pointy on Saturday 8th August 12:30

[WonkeyDonkey]

Have you tried CTRL+F5 to force a proper refresh of the page?

[Mr Pointy]

WonkeyDonkey said:

Have you tried CTRL+F5 to force a proper refresh of the page?

Yes, many times. No change.

[xeny]

Have you tried a fresh FF profile?

My very vanilla install loads that URL with no problems.

[SS2.]

Not sure if it's related, but the latest version of Firefox (v.79) caused problems with one of our own web applications. Something about it didn't like repeated background which made a right mess of rendering the pages.

We found everything displayed OK if you opened a new private window, but that wasn't a viable option for any of our customers who may use FF.

Might be worth trying for yourself, though ?

In the end, we modified all the affected web pages..

[Mr Pointy]

I've tried disabling every add-on & opening in a Private Window & it makes no difference. I'll try a fresh profile sometime.

[AJB88]

Just tried it on Brave browser and seems to load fine.

[Mr Pointy]

AJB88 said:

Just tried it on Brave browser and seems to load fine.

I know, it seems fine in Vivaldi & Brave. Interestingly I've just tried opening the page in Chrome & get the same issue as Firefox. The Chrome installation is up to date & totally vanilla with no extensions installed.