Nonce fails for logged in users

Hi there,

I’m running a multisite (subdirectories – setup), where my users log in at root level:

http://www.domain.com/login.php

This login uses ssl. Those users get a custom frontend-profil, also at root level:

http://www.domain.com/profile

Using ajax with nonces there works fine.

If those logged in users visit another site in my network, say:

http://www.domain.com/page2/

all nonces are failing there, because the current user is not set in the admin-ajax callback. So wordpress is checking the nonce created by user XY with the user 0 in admin-ajax.php. All the “normal” frontend functions on the sub-page, which get loaded during page build can see, that the user is logged in.

Maybe some issue with the auth-cookie, which is only set at root level? I have a test-stage environment, which is a copy of the live-site, except for the ssl encription. All the nonces are working there on every sub-page.

I have found a similar thread, but the solution isn’t working for me:
http://osdir.lowified.com/wordpress-hackers/2014-09/msg00031.html

Anyone has an idea? Thank you so much!