I am using a ftw.casauth plugin to authenticate with cas, it works when I click on the login link, but when I switched to intranet/extranet workflow I get redirected to my cas login page (as I should) but authentication fails and falls to local auth (plone user...), any ideas on what is going on here?
I have no idea, but you might want to check your logs, maybe there is something there, or you could add that yourself if the current logs do not reveal anything.
Can you reproduce it on a testing environment?
Here is what I get in fg mode:
2017-01-04 16:20:35 INFO ftw.casauth auth_fail is true, doc = <?xml version="1.0" ?>
<cas:authenticationFailure code="INVALID_SERVICE"> E_SERVICE_MISMATCH
This only happens if intranet/extranet workflow is selected
Maybe also ask the maintainers of that package. Is there an issue tracker for it? Also try Googling for that particular error message.