Never found a fix, I tried dynamic nav mesh generation, but it wasn’t performant enough to handle long ranges of motion, so if the player attacked outside the enemy range, the AI couldn’t find a path to them, and making it bigger was horrible on performance.
It’s now two years later and the project pretty much fell into an indefinite hiatus after that…
Been thinking of trying it again in newer versions of unreal in case that fixed it a few times, but just been more busy lately so… haven’t gotten around to opening the project again for quite awhile sadly.