I have gotten no answers from Bethesda on this, so I thought I would try here:
I play Skrim SE in Windows 10 with Vortex. I recently downloaded the Skyrim Creation Kit from Bethesda and installed it according to instructions:
http://tesalliance.org/forums/index.php?/tutorials/article/161-skyrim-se-creation-kit-installation-updated-may-2020/
The first time I tried to use it, I got a mysterious error message:
Experimental::RunOptimizations: (2460 + 59 + 330 + 532244) = 535093 patches applied in 673ms.
Terrain build dispatcher created.
DEFAULT: Setting key 'sControlsDefinitionFile' already used in list.
Setting keys must be unique.
DEFAULT: Setting key 'fMaxDistanceMoved:Pathfinding' already used in list.
Setting keys must be unique.
Creation Kit SE
User Name: XXXXX
BSBizIntEventHelper: GenerateUuid: 5eb3d04d-3ad5-4230-9300-1a08dd42b967 (5eb3d04d, 3ad54230, 93001a08, dd42b967)
BSBizIntEventHelper: GetPersistentUuid: eb6559c7-a372-488b-97cb-f7094e650cae (eb6559c7, a372488b, 97cbf709, 4e650cae)
LogEventToBNet: Event logging disabled. Skipping event send.
FaceFXWrapper could not be started (2). LIP generation will be disabled.
MODELS: Could not find model Meshes\Sky\Atmosphere.nif
MODELS: Could not find model Meshes\Sky\Clouds.nif
MODELS: Could not find model Meshes\Water\DefaultProceduralWater.NIF
MODELS: Could not find model Meshes\TranslateGizmo.NIF
MODELS: Could not find model Meshes\RotateGizmo.NIF
MODELS: Could not find model Meshes\ScaleGizmo.NIF
MODELS: Could not find model Meshes\PrimitiveGizmo.NIF
I don't know what it means, and no one seems able to explain it. The Creation Kit seems to be looking for .NIF files that are not on my machine, as so far as I can tell, not in the game at all. (Maybe from Oldrim?) My data did not load. When I click "Data", I just got an empty window. Following advice from another forum, I introduced exceptions to the virus checker, ransomware and the firewall, then ran the kit as Administrator. This made no difference. I also added a couple bug fixes from Nexus:
https://www.nexusmods.com/skyrimspecialedition/mods/20061/?tab=forum&topic_id=7197106
https://www.nexusmods.com/skyrimspecialedition/mods/2786?tab=description
These did not help. I tried running the kit from different folders, which did nothing. I tried uninstalling and reinstalling, and then it wouldn't run at all. So, I am out of ideas and hope someone here knows what's going on.