I can't access the full story but I suspect a company has to be an Argonaut client to make the list.Argonaut cover and have raised cash for SO4 and AMN.
AMN have probably dropped off because their PFS capex blew out and their opex costs are on the optimistic side with particular reference to royalty assumptions.
SO4 are on plan C or D but may have last found an option that will lead to actual development with the JV with Blackham. Their plan A at Lake Wells as a JV with APC makes a lot of sense. Why duplicate everything on one lake? The Blackham JV is probably why they made the cut. It should be an easy small scale operation that will generate some income to help develop their original assets.