I guess you found a bug since it says you are lacking
The client obviously attempts to send a sort order along with the create command because you dragged the channel into a certain position, but you don’t have the required privilege to do so.
The client should have realized that and just set the parent channel and no sort order, but it obviously didn’t.
Actually, it would be very smart to visually indicate valid drop targets so you don’t even try to drop a channel where you have no permission to drop it.
As a suggestion, I would probably do the following:
- make all invalid drop targets semi-transparent
- only show the green target indicator line if the target is valid
- attach a sign to the mouse cursor until it hovers over a valid target