You have a column to set a Milestone to Active/Inactive. Also a trash icon to delete the type.
It is assumed that your able to make inactive a Milestone type to prevent new ones being made on that type, but retain the milestones using the type already. Also, its understandable that deleting a Milestone type involves removing related milestones.
The issue here is that when setting the Milestone type to inactive is desired, app wants to you delete related milestones, which doesn't make sense as that is the goal of the trashcan to check.
Please align "Active/Inactive" check box with assumed behavior.
Thanks,
Nitisha