If you are playing according to WFB rules, it was always the case that the command group must be placed in the unit's front rank, and will move automatically if the unit reforms.
For example, 8th edition BRB p .82:
Any models that make up a unit's command group must be placed in the front rank of the unit, unless there is not enough room for them to fit. Where this happens, as many command group models as possible must be placed in the front rank and any remaining models are placed in the rank behind.
If the unit changes formation then the command group automatically pushes its way back to the front. Accordingly, when a unit reforms, the models of the unit's command group must be repositioned into the unit's new front rank as described above (regardless of the distance).