NPC's from my game have been dying mysteriously and I have found the cause they are falling through floor and dying. Why is this happening? Could it be open cities?

0 0 Skyrim.esm

1 1 Update.esm

2 2 Dawnguard.esm

3 3 HearthFires.esm

4 4 Dragonborn.esm

5 5 Unofficial Skyrim Special Edition Patch.esp

6 6 Cutting Room Floor.esp

7 7 SMIM-SE-Merged-All.esp

8 8 Modern Brawl Bug Fix.esp

9 9 Skyrim Particle Patch for ENB - Flame Atronach Fix.esp

10 a dD - Realistic Ragdoll Force - Realistic.esp

11 b icepenguinworldmapclassic.esp

12 c transmutelessmagicka.esp

13 d tes5merged.esp

14 e Run For Your Lives.esp

15 f CFTO.esp

16 10 Cowardly horses.esp

17 11 Whistle.esp

18 12 RichMerchantsSkyrim_x5.esp

19 13 SlightlyFasterHorses.esp

20 14 FNIS.esp

21 15 SSE High Quality Music.esp

22 16 Argonil's Unique Items.esp

23 17 longerblessings.esp

24 18 The Paarthurnax Dilemma.esp

25 19 When Vampires Attack.esp

26 1a Open Cities Skyrim.esp

27 1b Bashed Patch, 0.esp