I don’t know if I can help someone, in my case, in the Plesk web panel I had a “Web Application Firewall” activated for all domains including where I was trying to install Site Kit.
I’ve disabled during the setup and everything worked fine.
Having the same problem. I’ve set up my own server on Digitalocean with Plesk.
I’m having the same problem using the latest version of jetpack with photon activated, it simply breaks the image url’s and the images stop’s working. Is there anyway of make it work still using photon ? Any suggestions ?