Just checked the SPT discord and I saw as a reported bug that the "enable practice mode" box is not hidden. The bug description added that unchecking it would cause the game world not to be created. I'm completely new to SPT, so I was indeed unchecking it. That did not seem to cause adverse issues playing as a PMC, but perhaps the scav issue comes from this.
I cannot test this right now as I'm at work, but if you're encountering the same problem you could maybe try this.