Navmesh does not generate correctly around HISM instances when one instance has its transform updated. The most noticeable change is that adjusting the scale of an instance's transform will cause the navmesh to no longer generate on top of the instance or properly cut out around the sides of the mesh. Updating the transform of a single instance will also cause all of the other instances to no longer influence navmesh generation correctly.


Adjusting other transform values such as location also causes odd navmesh issues. Changing location of an instance caused some of the other instances to cease influencing the navmesh but the moved instance and one other nearby instance had navmesh generate correctly for the instances.

Steps to Reproduce
  1. Create a level with navmesh bounds
  2. Set navmesh generation to Dynamic
  3. Create an Actor BP and add a Hierarchical Instanced Static Mesh component to it
  4. Set the mesh of the HISM component to use a cube
  5. Add multiple instances to the HISM within the navmesh bounds of the level
  6. While in PIE, update the transform for one of the instances of the HISM by changing its scale

Expected Result:

The instance that was altered has the navmesh around it changed to reflect the changes to its transform and all other instances are unaffected.

Actual Result:

The instances are ALL updated and the navmesh no longer generate on or around them properly. The navmesh generates as if the mesh instances no longer are present in the level.

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ComponentUE - AI - Navigation
Affects Versions5.3.2
Target Fix5.4
Fix Commit32337041
Main Commit32337061
Release Commit32499825
CreatedJan 19, 2024
ResolvedMar 19, 2024
UpdatedMar 27, 2024
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