Enemies not spawning in presence of a Tusk Bolkor

Just failed a Bounty 5 last mission (sabotage supplies) because enemies refused to spawn.

The only thing present was a Bolkor, after destroying it enemies spawned again. However I didn't manage to do this in time, and the timer hit 0 (fun fact: while the last supply drop was on the fucking ground in front of me. How does that make sense?)

Just a heads up for people that might run into the same issue.