Your private topics community menu link was using that icon. You could not see in the config because it was not available in the selection list anymore.
I will see if I can do a usability tweak, e.g. having a 'deleted' option on that menu that maps to no icon when saved. But I edited your menu to resolve.
I will see if I can do a usability tweak, e.g. having a 'deleted' option on that menu that maps to no icon when saved. But I edited your menu to resolve.
Cheers
Ade