Opt-out iFrame doesn't work across domains

Hello, my Matomo installation is on matomo[.]mysite[.]com, and I’m tracking visits to myclientsite[.]com (well, not those domains, but that’s the idea). I’ve set the opt-out cookie in my Matomo settings under Personal > Settings, and it’s automatically applied in the GDPR opt-out too, but when I visit myclientsite[.]com, my visits are still tracked and the cookie doesn’t appear in local storage.

Anyone know how to fix this, especially with the GDPR opt-out? Is it to do with Safari’s automatic tracker blocking? Thank you.

Hi,

I’m not sure why this doesn’t work. Can you maybe send me the URL to the website as a private message so I can test it myself?