Rusk Industry Tokens not dropping in Elite Valley Frontier

[Neutrone]

They drop in Elite greensap farm but not the frontier. For more context I was playing Solo Elite Valley Frontier, my lvl is 81, I've ran about 5 times now and not a single token has dropped from the mobs. Could someone look into this?

[Futumsh]

I think that's expected due to the way that zone works.