I'm using Mibew 3.5.2 - the link you included seems to suggest it was fixed in 3.5.0? Perhaps it is not the same issue?
No, it's the very same issue. I'm afraid you don't get the point. The case when Mibew falls back to window-based mode is not an issue, it's a solution for the issue, because it's the only way for Mibew to be able to work when it's impossible to set cookies in iframe-based mode. And the 404 errors you see is the result of the check of possibility to set a cookie. See
the code.
Again any help would be greatly appreciated - we're finding that users are struggling to use it in the windowed chat as they 'lose' it behind the website page and don't know how to get back to it!
At the moment there are two possible ways:
1. One could use the same domain for Mibew Messenger and the site. They could be used on different subdomains, but the basic domain should be the same. Otherwise cookies in iframe will be treated as third-party and could be blocked in browser due to privacy setting (which is obviously impossible to change from aside) despite being marked as
SameSite=None.
2. One could somehow convince users to allow third-party cookies for Mibew Messenger.