Just a note here on something you mentioned above:
We tested in the Player Client as well and it would appear that the Player Client is also broken as it did not occlude the model behind the default occlusion model or the ones we tried importing.
How were you able to test this? When any portion of a model is visible to the "camera", it cannot be occluded.
(this was sometimes not true before the recent work/updates, which is why the work was necessary)
Occlusion assets have to completely hide other assets from the cameras field of view before the objects intended for occlusion are occluded, however, this isnt always perfect, but the work atm has far improved the reliability of the occlusions.
The stats are the only way to determine that occlusion is taking place.