M4084 - Problem adding new volume to group

My problem is that the system does not let me add an additional volume to an existing. The only way I can do it is to remove all mapping and remap. This just can not be correct and I find it frightening. Surely no one would done that.

The error i am getting is....

My environment consists of 1 Host Group which connects to my 3 VMware hosts and there associated Initiators (6 in all). I then have 3 volume groups (STD, Performance, Archive). Each of these groups currently each have 2-3 volumes currently mapped.

I am new to this storage and which to ensure I can setup and grow the system if needed. Also need to be comfortable that any changes made (micro-code, firmware, additional disk drives) will not impact the system or cause an outage.

Can anyone assist me with this?