Group Deed Objects listen() deaf!

Heres an interesting bug for you.

Scenario.
Have written a security sensor grid to be used over a large area of sim for which we have no estate tools. Certain commands tell nodes in the grid to do something, then shout out the associated command to other nearby nodes on a private channel, and so on. there are mechanisms in place to avoid chat looping.

Anyway, due to the land being group deeded, these objects need to be group deeded to for the management tools to work

Heres the Bug
*Object using and open llListen() ie llListen(channel,"","",""
*Both owned by me - they can chat to each other and hear each other
*One owned by me, One group deeded - they can chat to each other and hear each other
*Both Group Deeded - Can Chat to each other, but are deaf and cannot hear each other

This has been around in both 1.5 and 1.6. unsure about previous versions.

Can anyone confirm that this is not just me, and any thoughts why this may be happening, and when to expect a workaround/bugfix

Confirmed, I created a simple listener that'd say if something's in the same group, and deeded it to group, it would not respond to the other test object or my own chat, this is broken behavior I've heard talked about in 1.4 as well as 1.5 and now 1.6.

File a bug report, folks.