Dan,
The bottom leader is associative in that it points to the Mtext & the Mtext points to the leader and the reactor is set up in both.
When you move the text does the leader not react to the move?
In the entity list of the Leaders, both leaders have 3 points. In the bottom leader the HookLine is set to 1 as Kelie said.
With that option the middle leader point is not shown as it is not modifiable by the user.
It appears to me that to turn that option on the leader must be made associative. Or this may be a bug in ACAD2000.