OWA2013 some requests breaking APM session

Hi again,

it was hard to find useful words for the topic so let me explain my issue or lets say two issues:

When doing the logout from OWA, I'm issuing a redirect to the APM hangup URL when the logout URI is identified in the HTTP_REQUEST-event. This works fine and the APM session is also correctly deleted. But I identified that there is another automatic request issued (in the background) after this hangup-redirect towards the URI /owa/ev.owa2 (I guess this is related to the Enterprise Vault integration). But this request starts a new ASM session and when I click the link for a new session on the APM logout page, I'm always ending up with the error message:

The resource you are looking for is temporarily unavailable.

The cause may be an incomplete access policy evaluation. Please continue to finish your access policy in the previous browser window, and close this current window immediately.
Sometimes when I start a complete new session (even with a fresh browser window), I'm also ending up with the above mentioned error message. I found out that there are two different URIs also issued somehow in the background. At that time I'm also seeing for a short moment OWA trying to login and I'm wondering how the APM can be "bypassed" (is this some kind of caching misbehavior?). These two requests are also creating additional APM sessions and breaking the normal logon behavior:

/owa/sessiondata.ashx
/owa/userspecificresourceinjector.ashx

Not sure if both issues have the same or at least similar root causes. I already tried to catch these three URIs within the ACCESS_SESSION_STARTED-event and delete the access session again. APM redirects then to the URI /owa/?bO=1 with the above mentioned error message and I tried to catch this again within the HTTP_REQUEST-event and redirect it back to /owa/ and deleting the MRHSession and LastMRH_Session cookie. But without success.

Has anybody an idea how to fix that or can point me in the right direction?

Thank you!

Ciao Stefan :)