"Spirit Blade" Trait bugged/doesn't activate

Still having issues with Spirit Blade not firing. The "solution" suggested here does help it fire more consistently, but it is far from being a good work around. I did a bit of testing myself and found that even after 4 light attacks, the spirit blade often doesn't fire if there was any delay in the attack chain. This seemed especially true between the last light attack and the heavy attack.

This is a serious problem for a class and specialization that needs to be on the move constantly in combat to survive, particularly in higher difficulties. As the OP suggested, the trait should just convert your heavy attack to Spirit Blade. If that somehow seems too overpowered, make the trait always trigger Spirit Blade from Heavy Attack if the target has an Arcane Bomb.