Safari is no longer accepting login details for a particular website

This issue appears to only occur with one website https://www.echidnaonline.com.au/password/cs_password.cfm?ot=e, and only appears to impact iPhones that have had their browsing history and website data cleared.

For example:

• Person A can not login to the above website on their iPhone, yet can login to the same website address using a colleagues iPhone (Person B). Person B has not cleared history or website data.
• Person B can also not login to the above address using Person A's iPhone
• Person A's iPhone can be used to access other websites that require login credentials, i.e. online banking websites, without an issue.

I have also tried to download an alternate browser (Chrome) yet this has had no impact on Person A's iPhone and the same issue is encountered.

All login credentials are correct. I have contacted the website administrators and they do not have any answers nor have they had other reports of this issue.

Can anyone offer any solutions?

Thanks