It isn’t a bug. Here’s your Barbarian…
The Cube is showing The Furnace, Aquila Cuirass, and an empty slot, which must be filled with a Ring of Royal Grandeur as you’re getting the full 6-piece bonus of the Wastes set and Captain Crimson. That leaves just the season’s 4th slot available (which doesn’t show in the armoury pages) and that means you’re missing Ambo’s Pride and/or Lamentation. You also don’t have Rend/Bloodbath in your abilities. You don’t have Obsidian Ring of the Zodiac / Band of Might / Flavour of Time, so you’ll struggle to maintain 100% up-time on Wrath of the Berserker and lack mitigation. You really should read this…
Specifically for Season 22, you should be using the following…
Equipped weapon 1: The Slanderer
Equipped weapon 2: Little Rogue
Equipped ring 1: Focus
Equipped ring 2: Restraint
Equipped amulet: Flavour of Time
Equipped belt: Lamentation
Cube Weapon: Ambo’s Pride
Cube Armour: Mantle of Channelling
Cube Jewellery: Band of Might
Cube Wildcard: Obsidian Ring of the Zodiac
You can use Bul-Kathos weapons for speed-farming instead of Istvan’s.