It means that Appx found an unexpected entry in a "scope list".  
When you open a file, Appx creates a "logical file block" (LFB) to keep track
of that file.  Every file is opened at some particular scope - when that scope
ends, the file is closed and the LFB is discarded (a scope is something like
"the most recently invoked related process", "the current event point", or
something like that).  The LFB is linked into a list of all LFB's belong to a
given scope.  This message means that Appx was processing a scope list and
found an LFB that should have been linked into a different list (because it
has the wrong scope).

It could be related to FLEP bug.