Got a really short and sweet patch for you all. Turns out I managed to miss a checkbox allowing the new shotgun, flare gun, and their ammo types to be held with a toggled grip. This bug only affected those who had the toggle grip option enabled in the first place, so if you hadn't noticed or thought it was fine already, that's probably why.
So here's the patch note:
Fixed not being able to toggle grip on:
Thanks to the user who commented on the Version 1.1 announcement with the bug. If you'd like a centralized place to post about the game and report future issues and ideas, join the Discord!