Date & Time: 6 February 2019 (The bug has been happening since I returned to the game in mid-January)
Frequency: Every time I switch HUD Layouts via macro syntax or keybind.
World name: Shiva
Character name: Gareth Firmstrider
Retainer name: n/a
NPC name: n/a
Monster name: n/a
Class/Level: Any class, any level
Party or solo: Both
In-game time: Anytime
Area and coordinates: Anywhere
Housing: n/a

  1. >Character Configuration/Hotbar Settings/Display/Pet Hotbar Display Settings/Pet Hotbar Auto-display Settings
  2. Select "Display both pet hotbar and hotbar 1."
  3. Exit configuration
  4. Switch to another HUD Layout (i.e., 1, 2, 3, 4) via macro syntax or keybind.
  5. >.../Pet Hotbar Auto-display Settings
  6. Setting has switched back to "Display only pet hotbar."
(Change may also be observed outside of configuration settings while riding a mount that has vehicle commands like the cavalry drake or magitek armor.)