Hi, I have the latest versions of everything (steam fo3/nv, ttw, etc) and I am getting the same issue these people have uploaded images of. It only happens with certain trees and the LOD does not go away.
I first noticed this when I wanted to expand my LOD and made .ini terrain changes, they did nothing (besides cause this) and reverting to the backups I made beforehand fixed nothing. I don't know if it started happening before or after that but it's extremely hard to look at and happens everywhere. I am going to assume it did not happen until said .ini changes which means my installed mods are not relevant. I don't know if this happens in NV because I have only been in DC.
I have been trying to fix this for the past 4 hours. I have looked everywhere online and the only solutions I have found are "New Vegas generates LODs in a static file" and "GECK! GECK! GECK!" Also "problem fixed" which is my favorite, because it's obviously not. I have tried so many things between changing my LODs, deleting any LOD files I can find to regenerate them, looking for any mods or hotfixes I can apply, there is no solution. Is the answer really open the game world in a map editor and start manually rebuilding everything to remake LODs? I am really sick and all I want to do is eat soup and play my video game in what free time I have. This has been a nightmare of an experience.
If anyone sees this, thanks. If this can't be resolved I don't think I'll keep playing (it's a big issue).
edit: I fixed it. Or I mean delta534 did. https://taleoftwowastelands.com/comment/25024#comment-25024 If you see this then thanks for the patch, I'm not sure how it works but it does.
edit 2: For a more involved (but complete) fix do what RoyBatty suggests below.