[Answered ]-CSRF issue with Microsoft Edge and IE11

2 hours later, and I found the answer myself…

To those who might have the same issue with Microsoft Edge and IE11, the fix lies with the setting CSRF_COOKIE_DOMAIN.

I tried setting it like this:

CSRF_COOKIE_DOMAIN = "subdomain.domain.com"

However, that did not work, even though it was a subdomain site. Setting it like this works like a charm:

CSRF_COOKIE_DOMAIN = ".domain.com"