problem effectively was just known "port flapping on ports 6-10" (from ROS 6.36.rc20 renamed switch 2, finally) you can see topics here http://forum.mikrotik.com/viewtopic.php?t=104622
and here http://forum.mikrotik.com/viewtopic.php?t=104622
We solved only through a new official OS by Netinstall http://wiki.mikrotik.com/wiki/Manual:Netinstall
and after updating (as e-mail received from support) to last RC version. Only now there are residual re-login of customers group, but it appear without a specific cluster. But since we use UBNT Rocket at moment (https://www.ubnt.com/airmax/rocketm/
) we need to investigate if there is caused by them or what other.
P.S. host section was empty because that ports on RB3011 are not software bridged nor setted as master/slave (as you can see on previous screenshot there are 9xISP and 1xLAN with PCC). We are sure now of no failure for it because tested on an older RB1100AHx2