Question:

Why is the Entry Criteria to ensure all previous milestones have an Actual Finish Date not enforced in Vault when populating the Milestone Actual Finish Date manually, or via the Complete Milestone workflow?

Answer:

This is working as designed, as the system allows for a Milestone to be completed when the previous Milestones do not have an Actual Finish Date, in case the Milestone dependency between the two Milestones is set to the Rollup dependency type.

This is the case even if an Entry Criteria is set up:

Related Documentation:

Vault Help Documentation: N/A