I did some maintenance on my load order and added a few mods. I don't precisely remember what I did or added, but I know I added the Project Nevada Extra Patch, Imp's More Complex Needs, Interior Lighting Overhaul, Stealth Kills Enabled, AllAnimalsFriends, Difficult Journey, Ambient Temperature and associated TTW patches. I also installed UIO, FNV4GB and the anti-stutterer. Now I'm getting a similar bug reported as the Nevada Skies issue. I fast travel to the Citadel, enter, and it's just patch of ground, ~15 NPCs clustered in one spot, and the weather is pitch black. Outside of the patch, it's completely translucent (not a void, however) and there's some grass growing.
Here's my load order:
FalloutNV.esm
DeadMoney.esm
HonestHearts.esm
OldWorldBlues.esm
LonesomeRoad.esm
GunRunnersArsenal.esm
CaravanPack.esm
ClassicPack.esm
MercenaryPack.esm
TribalPack.esm
Fallout3.esm
Anchorage.esm
ThePitt.esm
BrokenSteel.esm
PointLookout.esm
Zeta.esm
TaleOfTwoWastelands.esm
TTWFixes.esm
Project Nevada - Core.esm
Project Nevada - Cyberware.esp
Project Nevada - Equipment.esm
Project Nevada - Rebalance.esp
Interior Lighting Overhaul - Core.esm
Interior Lighting Overhaul - L38PS.esm
Ambient Temperature.esm
Project Nevada - Extra Options.esm
Project Nevada - Rebalance Complete.esp
Project Nevada - Cyberware Additions.esp
Project Nevada - All DLC.esp
TTW Vehicle Scavenge.esp
Interior Lighting Overhaul - Ultimate Edition.esp
The Weapon Mod Menu.esp
TTW_SuperMutantRebalance.esp
TTW_StashPackOptions.esp
TTW_StartupMenu.esp
TTW_OutcastTrading.esp
TTW_NoKarmaDCFollowers.esp
TTW_MoreCookingItems.esp
TTW_Reputation.esp
TTW_Bobbleheads.esp
Project Nevada - TTW.esp
ProjectRealityMkIv5HDR.esp
TTW_XPReduction.esp
Delay DLC - TTW.esp
Imp's More Complex Needs.esp
Ambient Temperature - IMCNNV.esp
Imp's More Complex Needs - JA - SORTED.esp
Imp's More Complex Needs- All DLC and Alcohol Overhaul + Nuka Fix.esp
ILO - Project Reality Patch.esp
ILO - GS Shack.esp
ILO - Tale of Two Wastelands.esp
AllAnimalFriends.esp
Stealth Kills Enabled.esp
TTW_Difficult_Journey.esp
IMCNNV - HUD and Hotkeys.esp
imps_more_complex_needs_-_tale_of_two_wastelands_patch_0.esp
Total active plugins: 56
Total plugins: 60
I've traveled to the Citadel before and had no problems. It must have been something that I did today.