Hi Roman,
Yes I know how to activate the monitors, I've already previously activated them. Here is the thing: So as of today all the server nodes are reporting monitoring data without issues, however this weekend the system will restart (it restarts every week .... don't ask me why my company has this policy in place). After the restart, some server nodes will come fine, some others won't have the main sub-tree nodes active as you see in the first picture. When this happens not even trying to re-enable the monitoring on the faulty nodes works; then the only solution here is to go node by node and restart the MONITORING service. This takes a couple of seconds for each node but considering the amount of nodes in our system it's not a feasible procedure to follow every Monday.
Thanks and regards