I had that exact same issue, after troubleshooting I discovered that The Weapon Mod Menu was the culprit. I had put it in the wrong place in my load order.
Are you using that mod? If so, is the plugin near the top of the load order or the bottom?
I had mine near the bottom of my list and after running BOSS, it had moved it much closer to the top, and the problem disappeared and never surfaced again.