RAC - 12.1.0.2: How to deal with a high score of "CSS group membership query" wait event?

hi gurus,

my architecture is RAC - 12.1.0.2 - OraLinux 6.5 - two nodes:

How to deal with a high score of "CSS group membership query" wait event?

Any suggestion related to

- What this event is?

- Possible cause of such a high score (it's the top wait event)?

- where to find docs about it (it's not well documented)?

The scoring of this event seems to be related to a bug of the 11.2.x version.

I applied the same workaround related to that version (stop/restart of the cluster) but after two days of run the scoring of this event reached the top of the ranking...