All downstream features on linked mirror parts automatically disappear

There are a few scenarios where downstream features created after the linked mirror feature will disappear without any warning.

Scenario 1 - When the "Delay Link Update" is turned ON and Assembly Load Options has Load Interpart Data turned ON:

Loading the target linked mirror part into NX session, the Part Navigator shows the expected downstream features after the Linked Mirror Body feature.

Once the target file is loaded, toggle OFF "Delay Link Update". Notice all downstream features disappear without any warning.

Scenario 2 - When the "Delay Link Update" is turned OFF and Assembly Load Options has Load Interpart Data turned on:

Loading the target linked mirror part into the NX session, the Part Navigator is missing all the downstream features below the Linked Mirror Body feature.

Why is the downstream features in the target file missing when the Link is updated?

The behavior of those downstream modification feature disappearing on the target part is due to how that target part was initially created.

During the command Create Linked Mirror Part, this option below will determine how the downstream modification features are to be treated.

Also by looking at the Part Properties of existing target linked mirror part, this attribute tells that it was created using "Exact Mirror" option:

Based on NX Help Doc, this "Exact Mirror" option will cause all downstream modification to be lost, thus making the part show the EXACT REPLICA of its source. This is the intent of "Exact Mirror" option.

If the workflow requires downstream modification to remain on the target Linked Mirror part and not get lost, then the correct options should be one of the "Non-exact Mirror" option.

For an existing file, proceed with edit the above attribute in the Part Properties dialog and change the value to one of the “Non-exact Mirror” option, OK the Properties dialog, save and close the part. Now upon reopening the part, all downstream features will remain, regardless if source part has been modified or not.

https://docs.sw.siemens.com/en-US/doc/209349590/PL20231101866122454.assemblies/xid384604