Invincible not unlocking
hi, i've done the game 3 times now and the achievements hasnt unlocked.
i've done it on easy and got all weapon achievements.
so went through again on easy till last checkpoint, saved then return to hq, changed to formidable backed to hq so it saves then back to title screen then gone to continue last check point and finished level on hard, i then changed back to easy and carry on. should i at this point back out to title or am i ok to change to easy then carry on?