If you aren't the leader of the island and your leader is offline and then you try to mine, it won't generate the other ores only iron and cobblestone. That's how it works here even though you bought the upgrades yourself even though you are not the leader those are just wasted money unless you make your own island or your current leader gives you the ownership of the island.
Gold, diamond, emerald, etc. can only generate when the leader of the island is online.