In a specific area in Titan’s Canyon, my Hungering Souls spell is invisible. It appears like a layer bug, as i can cast on the edge of it and see the projectiles disappear as they reach the area.
For me, this was happening in the sandy area after the meat grinders where theres a red tattered carpet on the ground.
Screenshot here:
I was trying to find a good way to report this issue, as well. In my case, Marksman with Cinder Strike. The animation would play, but the projectiles would disappear, and - crucially - not hit enemies/breakables, even when directly targeted. Acid Flask worked fine, but arrows went poof.
Same issue with puncture arrow, but on the bridge just past the waypoint for me.