IDP 5 - NoSuchConversationException when clicking URL link from email and _saml_idp cookie set.

[Cantor, Scott]

I would add for the archive, I think the only reason it "works" a little in your Strict scenario is the domain match. That results in the sites being handled as same-site (if not same-origin) and your cookies work. That's obviously specific to this case but not generally functional.

With my IdP set to Strict, simply clicking a link to an SP in a different domain in any context breaks it. No workarounds possible there.

-- Scott