I've been noticing this issue more and more lately, mostly on my Stronghold build (because you block a lot more on that build). Frequently after guarding with a sword for a while, and then swapping to a different weapon, I cannot use my melees, even though they're fully charged. Usually the only way to fix this is to try repeatedly swapping back to the sword, or swapping back and blocking, and then swapping off the sword again. That only works some of the time though. The only truly reliable way to fix the issue is to die, which isn't a great solution for content where revives are limited, or you're trying to go flawless. Given how popular Stronghold is this season, with the Praxic Blade, it would be nice if you could fix this extremely annoying and often fatal issue, especially since it's been in the game since Final Shape, or possibly even longer.