I have the mod downloaded, with a few other addons, and it stopped working a little while ago. I have no idea what could be causing this, but I do have a small list of addons that may be causing the issue.
(While I do not know the names of the addons, I will describe them to the best of my ability.)

Model replacements for all weapons
Immersive camera (basically when you look down, it shows your playermodel.)
Viewmodel lagging