if you have problems with the seeker Achievement and you get very frustrated. Here´s the solution to handle it easy.
Go xbox home > settings > system > storage > select harddrive and press Y (device options) > clear system cache. Now start playing but dont download update. Then go to oil rigs and collect secrets and u should get seeker achievement.
THX go out to timpeee
it work for me and i´m happy, that i´m get these glitched-achivo!