Ok Red51, We have been checking. So here is what we have. If one person is on a mount and someone tries to invite to group it either will not work or it bugs it. This is with all mounts.
Second thing It places a black x on the map of the other person instead of a red dot. I dont know which way you have it setup. Because most of the time it is a red dot which we like better than the x.
But join group does work for the most part if both people are are off mounts then making the group.
Also , Now we tested another part of it and I dont know if this is supposed to work or not. But we had three of us running together. So person A asks person B to join join group those two can see one another. Now if person A or B ask person C to join then person C can ONLY see person A or B that asked them to join but can not see the other person.
So person A asks person B to join both can see one another. A and B are in group now person A asks person C to join group Now only person A and C can see one one another and Person A who asked both person B and C can see both of them. Both C and B can see person A. But C and B cant see one another.
I hope this helps. Thanks