per_instance coverage

Hello,
My eVC has a configurable list of agents. Every agent in the list may be of kind SLAVE or MASTER.
Of course, every agent kind has some configuration fields in common and other fields are idividual to
SLAVE and MASTER agent kinds.  Hence,  the configuration struct looks like this:

struct my_config_s { agent_name : agent_name_t; agent_type : agent_type_t; a : uint(bits:5); event my_cov_ev; cover my_cov_ev is { item agent_type using per_instance; item a; }; when MASTER config_s { master_b : bool; cover my_cov_ev is also { item master_b; }; }; when SLAVE config_s { slave_b : bool; cover my_cov_ev is also { item slave_b; }; }; };

I can see in the coverage browser that every cover group instance for every agent has all possible cover items no matter of the agent kind. The strange thing is, that I see e.g. the master_b cover item incremented inside the cover group for the agent of kind SLAVE!. What I would expect is that every cover item added by e.g the MASTER "when" inheritance is left empty ( = 0) and is never incremented inside a SLAVE agent kind.

Has somebody made the same experiance and an explanation for this behaviour? Do I miss something?

Thanks in advance,
bug_hunter