One test you could perform is to login to the problem machine with another profile to see if this behavior persists. If not, then there is most likely an issue with some component of the user's profile. A rename of that profile and subsequent login would create a new profile and most likely resolve the issue. If this doesn't resolve the issue you can open a support incident and we'd be happy to troubleshoot further.
Darron Hellmann, Sr. Technical Support Engineer, Okta
If there are individual users who need troubleshooting with IWA I alwatys ask them to access: http://<hostname>/iwa/Authenticated.aspx
Chances are if they can access IWA on firefox or Chrome with the above 'authenticated.aspx' test URL but not IE then they have disabled kerberos or another setting in IE. It might be simpler to redeploy default IE settings
We get this issue intermittently but regularly with different users and the only fix we have found so far is that use IE in in private browsing and then close IE and then open again as normal and it would work. It's still is a problem for users though. No solution yet.
We had this issue intermittently and it turned out to be our Meraki firewall content blocker. Why it didn't happen everytime I can't say. After whitelisting sites assoicitated with Okta signon the problem went away.