Break simulation

If analyzing the final plan is insufficient to determine why an operation is planned early on the bottleneck, there is an option to break simulation right after the operation is planned. You can use break simulation to display the situation exactly when the operation is planned and why the operation is planned as it is.

These are the other possible reasons why operations are planned too early on bottleneck resource:

Priority and pull-up
Use of earliest start on orders
You can use the automatic function Generic setting of due time and earliest start where you set earliest start based on offset from the latest start date.