/u/rebulast Entrati syndicate progression stopper:
Unranked syndicate: can only get 1 lure type.
To rank up: requires son tokens.
To get son tokens: requires at LEAST 2 lure types.
Son sells one lure type.
Hence, you cannot upgrade your rank.
It might be that they spawn randomly, but that is NOT something that should be relied upon.
EDIT: Okay, they spawn randomly, but I still consider it bad practice to rely on that. Not everyone comes up with that. Also, since tag rarity matters, it'll take hours upon hours to get 5 son tokens the first time.\
EDIT2: Ivara sleep and presumably equinox sleep make conservation animals uncapturable.