Weired redirect url after trying to login as non superadmin to one of my multisites

Hey guys,

every time i try to login to one of my multisites (except the #1 page) as a non-superadmin (as an Editor in my case) i get the following redirect url:

http://mydomain.com/dm-sso-endpoint/1430411591/?dm_action=domainmap-propagate-user&redirect_to=http%3A%2F%2Flaunch.mydomain.com%2Fwp-admin%2F&auth=myusername1430411651DFtnfjtgo2kSP818i24jxRVnpHml0YWqvtCCsRmL3bud612ba139d0855ae4f618fbcc1cdb28e4499ff42869e479f6e0a0a2610d564ee

Iam running Wordpress 4.2.1 and Domain Mapping 4.4.0.2.

My htaccess, wp-config and domain mapping settings are nothing unusual and everything worked just fine before the Wordpress 4.2 update.

I have no domain mapped at the moment, but the plugin installed and activated. If i switch it off, the problem is gone. Also switching off every other plugin did not solve the problem.

Best,
David