Currently only circuits that are on ways directly adjacent to each other can be grouped, eg 1L1, 1L2, 1L3.
It is common to require sockets which are physically next to each together in a space to be on the same phase, eg 1L1, 2L1, 3L1.
When phase balancing these circuits must be locked in place or Revit will move some or all of them and generally move them onto different phases than they were on before.
This removes the critical setup that has been created by the Engineer without raising a warning and potentially creating a hazard.
Fix:
Allow groups of circuits to be created that are not directly adjacent to each other and allow automatic phase balancing to move them as a group.