SSL certificate is not Standards compliant

Hi there,

In a bit of a pickle here. We recently renewed our SSL certificate we had the new version running for a few weeks with out an issue, then last Friday we started getting reports that people were getting certificate errors. Looking further into it I've managed to find out the following.

1. Certificate works on all browsers on widows
2. All certificate checkers (eg go daddy's cert checker, sslabs) have no issue with it.
3. Safari on MacOS (Big Sur) gets a 'Certificate is not Standards Compliant' error
4. Chrome on MacOS (Big Sur) gets aNET::ERR_CERT_AUTHORITY_INVALID error
5. Firefox on MacOS (Big Sur) works fine
6. Safari on iPhone works fine

I have tried contacting godaddy (provider of the certificate) and they've stated that it looks like a mac issue so are whipping their hands of it.

We still have a few weeks before the current certificate expires so I've been able to swap back for the main application but have left it on another version to try and figure it out. you can go here https://demo-catalogue.testgrid.com to see it occur.

I'm really stumped (particularly that it was working for a few weeks and then just stopped).

Any help/ideas would be much appreciated!