I'm using Blender 2.82a and I've made first-person arms for a game I'm working on. I had to add bone constraints to avoid the infamous wrist-twisting issue (copy rotation). All of my animations are on a single timeline.
However, when I exported the FBX file, it didn't contain the bones with the restrictions which resulted in... pretty awful looking animations and plus the textures looked bad.
How do I fix this issue? I googled and saw that most posts were for older versions of Blender so I didn't want to experiment on a newer one.