Permissions for Extensions in Safari Web App in MacOS Sequoia

Hi folks. So I am attempting to enable extensions in a Safari Web App (by clicking File → Add To Dock in the menu bar), but in the latest version of MacOS Sequoia 15.2, this does not seem to be possible.

If you open a saved Safari Web App → Settings → Extensions, you can enable the extensions, but on the right it simply says: "Extension_name does not have permission to read or transmit content from this app."

Does anyone know why this is no longer possible to enable extensions in Safari Web Apps, or what setting elsewhere needs to be changed to enable this permission?

Cheers,

Denis