As a Vortex user, I tried these steps. With many mods it was a bit time consuming but worth it as the entire procedure worked. I didn't really follow marnaz's update later (for me this shows on page 7 of the forum but your view could look different). I did make sure the acf file saved as "Only update when launched" per their suggestion. I did add in the step of saving the new version in a backup as well. The trick to this whole thing seems to be to get Steam to actually update the game so it clears as updated. Then, following these exact steps, you get the steamapps folder returned to its pre-update state with an appmanifest that is read only so will not enforce update. I will say when I opened Vortex I did not get any options. Everything looked okay and I did not have to address mod deployment manually (it possibly was doing it in the background?) or then, subsequently, choose "use newer files". I tried loading the game directly from Vortex as well as my pre-made link to f4se.exe and both work. I have all mods, the game continues where I left off. I've read that other ways to access this game allow you to block updates. It is sad that Steam does not. I have two games that are heavily modded and if I were faced with a situation where I have invested heavy (extreme) amounts of time modding and testing mods to make sure everything works, and tweaking and perfecting them, only to have that work totally 100% destroyed, I would not suck it up and play the game unmodded. I would uninstall it, delete the mods, and not play the game again. It was just too much work to be messing around with. Just make it optional... sheesh!