Update: This issue has been resolved. Moving a BrightWall between groups now works as expected.
There’s currently a bug associated with BrightWall groups in BSN: Attempting to switch a BrightWall from one BrightWall group to another will cause players within that BrightWall to become unresponsive. If this occurs, reassign the BrightWall to its original group. The players will become visible on BSN again the next time they check in.
We are working to resolve this issue; this post will be updated when a fix is applied to the BSN servers. Until then, the only way to assign a BrightWall to a new group is to perform the unit setup process again on players within the BrightWall.