Error trying to edit the navigation picture for messages.

When editing the profile pictures image (I was trying to edit it to be empty - https://2img.net/i/fa/prosilver/empty.gif ) it will throw and error reading "You must provide a menu name", regardless that a locked pre-specified menu name is already provided.

Is there a known fix for this, or is this a current bug?

Private Messages, New Private Messages, Log In, and Log Out has to be changed here:
Administration Panel > Display > Colors & Pictures > Pics Management
Advanced Mode
General/Index Tab

Thanks. Btw, I was able to edit login/out from the navlink editor, just PMs gave me an issue.