Add custom icons to columns in dynamics 365 V9 legacy web does not work

Hey, I'm trying to add custom icons to columns in dynamics 365 V9 Legacy Web but it does not work. In the unified interface this is working. I'm using the documentation here https://docs.microsoft.com/en-us/dynamics365/customerengagement/on-premises/customize/display-custom-icons-instead

Is this feature working only under Unified Interface? 

This is what I should see in Web:

But in Web no icons:

Thank you for any help.