Symptoms

After configuring working hours, escalations configured to execute after X many days do not seem to be firing at the correct time
 

Diagnoses

The "day" value in the Escalation UI amounts to 24 hours. After Working Hours are configured that equates to 24 working hours, not a working day. For example: If you configure a 12 hour workday, and an escalation is set to fire after 2 days, it will calculate 48 working hours, which will be 4 days later.
 

Resolution

You will need to calculate out the correct number of working days, or use hours instead.

In the above example: 2 work days = 24 working hours = 1 Day in Escalation UI. OR use 24 working hours in UI.