Didn't Receive Dungeon or Raid Loot While Running Solo

Participating in dungeons and raids 11 levels or lower than the character level will activate Legacy Loot Mode. On Legacy Loot Mode:

• Dungeons are treated as if a full 5 players are present, providing an equivalent amount of loot
• Raids act as though there are 20 players in the raid, providing an equivalent amount of loot
• All items on the loot tables have a chance to drop, not just ones that are designated for the character's spec
• If multiple players are in the party, loot is split among those players, but is tradeable
• It is possible for multiple of the same item to drop off of a boss encounter

These changes allow transmogrification collectors a greater opportunity at items from older content. Legacy Loot Mode was turned on with the Battle for Azeroth Pre-Patch.  

If the content is of a higher level then loot settings would be on personal loot, where you will only receive loot for your character with a maximum of 1 item per boss.