Hello again.  Today we finally solved the problem with a workaround. All problematic server's iDrac have been patched from 5.x to the latest 6.00.02.00 iDrac Version. After deleting and rediscovering them again in the OME, they were successfully assigned to a baseline. The Problem is weird, since previous installed iDrac Version was the same for most servers, working and non working.  In the end the iDrac update is a workaround we can live with. Hope this can help others. Thanks again to everyone.  
We are having problems with a newly created OME instance and its baseline. In total the ome instance has discovered 28 servers, which are shown as healthy. When we try to add of them to a general baseline, we can only select 15 of those servers.  The ome applieance has been restarted, without any changes regarding the problem. What could we do to be able to select all our servers as targets for a baseline? Thanks, Simon
Unable to select all devices, to add to baseline