Agile Stories show updated by a person who is not associated with Story when Global Rank re-evaluation takes place.
1. Hop on to Servicenow instance.
2. Create a story by impersonating a user.
3. Notice few other stories not associated with this user is being updated and updated_by for other is the user in Step 2.
The issue was happening due to Data corruption. The global rank data is corrupted, current last_index for rank_configuration is not having max global rank among the existing stories.
Run below script. It will stop same issue happening for future story creation.
var gr = new GlideAggregate('rm_story');
var rankGr = new GlideRecord("rank_configuration");
rankGr.setValue("last_index", gr.getAggregate("MAX", "global_rank"));