Where do I find the 'Due date' column in the activities Power-Grid?

The 'Due date' field is specific to certain activity types. Whether an activity has a due date depends on how that activity type is configured in the Configuration module.

Because the activities Power-Grid must display all activity types at once — regardless of your current filters or configuration — the 'Due date' value is consolidated into the 'Start time' column. This makes it accessible across all activity types in a single, unified view.