Nostalrius Begins - Quality wow vanilla realm (1.12)

If another player has tagged a mob, inviting him to the same group would make it from gray to red on retail, but it doesn't seem to work that way on nostalrius which leads to slower leveling. can it be fixed?

For clearification on what was possible in the blizzard servers.
If a mob was gray, you could join a group and hit the mob once then it would turn red and you would be available to share the loot.
This does not work on nostalrius and I think it is of high priority to fix.

confirming

Doesn't accepting the invite while attacking the mob cause you to gain half the experience cause you are now in a group?

yes, which currently does not work + you get no kill credit from the mob and no loot

Grouping really soaks up your xp, and I notice a lot of the people I've grouped with pretty much idle in one spot while I do all the tagging work which is not cool, I then just have to drop group and go on my way.