I do, but it simply says: "Blocked loading mixed active content "http://blah/blah/something.php?" [Learn More]
Clicking [Learn More] takes me to a generic Mozilla info page and says nothing more about my specific error.
Viewing post in Unity WebGL and CORS
I don't think mixed content refers to CORS at all. It's saying that you're loading an insecure resource (http://...) from a secure page (https://...). That makes sense actually. Itch serves everything from https so you'll need to load your analytics script from a secure server as well.
(The reason for the error, I imagine, is that otherwise the user is misled about the level of security on the page. It appears to be secure, but in fact it could be attacked by tampering with the insecure script.)
I don't know why that would be, assuming you've cleared your cache and everything. I haven't used Unity analytics. What happens if you change it to a completely different https URL? Do you get the new URL, but with http instead of https? Do you still get the old URL? Or does it actually work and you get the new URL with https?
Hey! Not sure if you still have this issue, I found this thread by looking for a solution myself.
I fixed the "mixed active content" error by switching to UnityWebRequest instead off the WWW class I was using. Seems the WWW thing defaulted to http regardless of what you wrote in the URL. At the same time I forced my server to only accept https, I did these at the same time so I'm not sure if the force https thing is needed. Hope it makes sense :)
(And check out my thing here if you want ;-) https://aergia.itch.io/the-city-haze )