Disable "add property" not working in New Web ?

Hi,
We have not observed such a defect in our case, which makes me suspect that there might be some misconfiguration in MDCC . This can happen with more complex configurations. Try moving this rule to the beginning of the configuration, defining it without any filters. This should hide the 'Add Property' link everywhere.

{
    "Name": "Hide Add Property Link",
    "Filter": {},
    "Behavior": {
        "MetadataCard": {
            "Theme": {
                "AddPropertyLink": {
                    "IsHidden": true
                }
            }
        }
    }
}

We already have this in config

The result:

while the same config exists in other classes;

the result;

I understand that you have created sub-rules for this in each class. My recommendation is to try moving the hiding of the 'Add Property Link' action into a standalone rule placed at the top of the MDCC. Use the code I provided without any additional filters.