Actually what might be 2 related bugs.
You have a group with 50 users, these users have a primary group and additional groups
Bug 1
you want to do a multi edit, you can only ADD these users to a new group, you cannot remove all the groups they are currently part of.
really in multi edit mode, for “remove” it should show every group the multi-edit membrs are in ,so tehy can be removed, but it does not, so you cannot remove them from groups, only add
bug 2, same with other aspects that have a “remove” function & list , it only works if you have a check box to select…
but in multi-edit the data is blank.