When the priority is changed for the parent record, the SLA timeline becomes empty.Issue The Service Level Agreement (SLA) timeline provides a detailed insight to the task updates which triggered stage changes during the life cycle of a task SLA.The issue is when the priority of the parent record is changed then the SLA timeline is not showing any data. Steps to reproduce: Create an incident recordCheck if the SLA is attached.Now change the priority of the SLACheck the SLA timeline where we cannot find the data.CauseThe custom business rules are causing the issue. On being checked, it was found that custom business rules are trying to change the parent record where the audit of the record would not be visible for the timeline to show the data and process the workflow. ResolutionThe below methods can be checked to avoid the issue:- Deactivate the custom business rulesCheck the customization