First of all the StaticMeshEditor_LODDetails Toolbar is broken. As you can see in the screenshot it only displays unrecognized tab. No LODs can be created as increasing the number and clicking apply changes just resets it to 1.
Also the LOD0 trianglecount can not be reduced, as changing the Percent Triangles to 50% and hitting apply changes does nothing to the Base LOD. This can be confirmed by placing the mesh in the level and changing the Force LOD setting from 0 to 1,2 etc which always shows the same original imported model.
Build info
Version: 1627304
Install Path: C:/Program Files/Rocket
Specs
OS: Windows 7
RAM: 6 GB
Graphics Card: GTX 560M w/ 1.5 GB
UAC: Off
Repro Steps
Import a static mesh.
Doubleclick it and change LOD Group to LargeProp (just as an example)
Change Number of LODs to 2 and apply changes
No LOD1 settings are available, so change LOD0 to 50% triangles.
Close the Mesh editor and click yes to apply the LOD settings.
Place the mesh in the level, it has no LODs even when Force LOD is changed to 0,1,2 etc.
Results
The imported mesh always has its original triangle count, no matter which LOD is forced to be rendered.
Expected
A LOD Model should be created after the Triangle Percent is set to 50% and the setting is applied.
Screenshots