Thumper Spawns broken (only 1 per Mission)

[ReniLuce]

I repeatedly tried farming Thumper yesterday for Friends, but always only 1 Thumper per Mission was spawning.
We even tried one whole Day-Cycle to search for them, none found except for the first one. (I know only one Thumper can be active at a time)

Maybe useful information:
- we selected the high level Bounty from inside the mission (more ressources)
- we always were flying very low or running around
- we left the Bounty alone every time, as we only wanted to ramp up the enemey lvl
- at somepoint we tried killing enemy troups, we thought they maybe block the Thumper Spawn

Not sure since when this is broken, or if we were doing something wrong ... maybe a year ago it was still working xD