Why does the ‘End voice’ appear randomly?
Maybe an XML import without having unchecked Preferences>MusicXML>Import>Rests>Rest Visibility?
If not: as always, please explain more in details the situation and upload a project, to see if there is something unexpected (but generally the Start/End Voice property doesn’t “appear randomly” but is activated manually, directly in the panel, or removing rests, or as I said throughout XML import)