Newly uploaded Unofficial Patch is broken, just a heads up for troubleshooting
I grabbed some weapon mods (Makeshift SMG, CWE Service Rifles, and Dak's Attachments) along with the Unofficial Patch (which has been gone for ages) and found none of my firearms (even vanilla ones) would work in 1st person. I thought it was some of my new weapon mods (new animations) as it was referenced on CWE Service Rifles but said to be fixed. Turns out the problem would only go away if the Unofficial Patch did, so save yourself some hassle in tracking down issues with your mods until it gets updated. On a side note all 3 of those weapon mods work as far as I've tested them, very worthwhile additions to your game.
EDIT: After some more testing I've found that the ammo conversion capabilities of the Makeshift SMG, which I love, is causing it to spawn on NPCs with the wrong ammo. So they have a decent gun but resort to fist fighting since they have the wrong ammo. That's really too bad since being able to use a bunch of different ammos in it was huge plus.