RESOLUTION SUMMARY, TLDR (see all comments for additional context):
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After completing the Bloodmoon main quest, actors are frozen in place once they detect you and become hostile. They can use melee/range/magic, but just can't move.
Using TESIVEdit, open "morrowind_ob.esm" and go to "script". Scroll through all scripts to "0101E4CD fbmwBMMissionaryScript". Right click it and in the context menu that appears, click "Remove". Wait for the "warning" timer to expire, and then click "yes". Close TESIVEdit, and it will save morrowind_ob.esm.
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Cross reference these posts:
https://tesrenewal.com/forums/morroblivion-problems/monsters-and-humans-no-longer-move-to-attack-me
https://tesrenewal.com/forums/morroblivion-problems/disposition-lighting-scripting
As stated in the title, at some point when playing Morroblivion, actors which turned hostile for any reason (whether by being attacked or being enemies that detected me, would freeze in place and not move towards me. They would still use magic, shoot arrows, and swing at me if I came in melee range.
The above posts suggested that some script was causing the issue. I discovered that if if removed OBSE from my Oblivion folder, this glitch went away. However, Morroblivion depends on OBSE.
After hours of editing Morrowing_ob.esm and deleting random scripts, I finally determined which script (at least for me) was causing the issue:
Using TESIVEdit, open "morrowind_ob.esm" and go to "script". Scroll through all scripts to "0101E4CD fbmwBMMissionaryScript". Right click it and in the context menu that appears, click "Remove". Wait for the "warning" timer to expire, and then click "yes". Close TESIVEdit, and it will save morrowind_ob.esm.
Now you should be good to go. Hostile actors can move again.

More of a Case of What is in
More of a Case of What is in your Load Order that Could be Causing the Problem.
Have never Had any issues with having to Alter the .esm or Scripts to Play and Do Not Have these Issues.
Only running Standard V 064 with out any of the Patches 211 Game Days level 30. 144 Quest Completed..
While you at there Post a Couple of Locations So I can do a Media Clip.
Go Load Order..or Have you Altered Animation in your Game.