Dead Rising 4

For this achievement you need to do the following:

• Complete all cases
• Unlock all skills
• Find all collectibles (panic rooms, blueprints, notebook items)
• Reach lvl 100 (required for all skills anyway)
• Complete all trials

If you pick up one of the skill books in multiplayer before picking it up in single player, it might bug and not unlock correctly in single player.
If this happens to you (it did happen to me) just complete all other unlock criteria but skills and then start a multiplayer game and unlock any skill.

This made the achievement pop for me (it still showed 99% completion and one missing skill though).