The way I handled it was rather than using a spawn volume, I used an actor as a spawn location and got a random point on the NavMesh within a specified radius.
Ignore the enemy check, I was limiting the number of spawn enemies in the level at any given time.
You might want to add a spawn sound so you know if it’s actually happening. I had my spawn point just a hair too low and it caused the enemies to collide with the terrain and either fail to spawn or spawn under the floor, either way, it looked like they weren’t spawning but the sound indicated the logic was still firing since it came after the spawn actor node.