Is OAuth (Impersonation) with crowd not enough anymore for SSO??

[PRISMA Computer GmbH]

We have following setup:

• jira + confluence on 1 Server with 2 tomcat instances.
• the aplications are using the context /jira and /confluence
• confluence uses jira user directory with type crowd. synchronisation is successful.
• user access both applications via reverse proxy. reverse proxy is setup correctly, using it's own proxy connector in both apps. healthchecks are ok.
• both applications are linked to eachother by OAUth (impersonation) and green (linked). (Internal linked by localhost, shown URL is the proxy URL)

Quite normal setup. As far as I can remember, I'd say SSO worked before upgrading jira to 7.3.3. After upgrade users have to login twice. Did I something wrong or is this intended behaviour with 7.3.3??

[PRISMA Computer GmbH]

PS: confluence and jira logs don't show any error regarding oauth. otherwise I had a point to start from to follow the documentation.