senatorhung wrote:
http://galaxylegion.com/wiki/index.php/Corruption_Market
might be a hidden rank restriction.
I can't say that's likely unless it was unintentional. Rank restrictions are usually placed on either missions or items, not upgrades or unlocks.
I asked when this happened, because the OP posted shortly after the daily backup. It might be possible that the unlock was skipped or lost if he tried to do it at the exact same time as the backup kicked in.