Linux (Vulkan / RADV): Viewport flickering, black missing meshes & "outdated swapchain" spam (RX 6600)

Development Rendering
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Hi everyone,

I’m relatively new to Unreal Engine and currently learning the ropes on Linux. I’ve hit a roadblock with a severe viewport rendering issue where meshes turn pitch black, disappear, or flicker when looking around the scene.

Looking straight up at the sky is completely stable, but as soon as I look at the village structures, the frame rate tanks and geometry breaks apart.

This issue persists across multiple maps and view modes (including Unlit and Base Color buffer visualization).

System Specs & Environment:

OS: CachyOS (Arch-based Linux, KDE Wayland)
GPU: AMD Radeon RX 6600
Engine Version: Unreal Engine 5.8 (installed and launched via Asset Manager Studio)

Video of it happening:

Some things AI suggested but didn’t help:

  1. Console commands: r.Nanite 0, r.Shadow.Virtual.Enable 0, r.DistanceFields 0, r.AllowOcclusionQueries 0, r.VirtualTextures 0 – none of these resolved the black/missing meshes.
  2. Verified in Unlit / Base Color view modes – the geometry remains broken and black.
  3. Attempted switching TargetedRHIs to SF_VULKAN_SM5 in DefaultEngine.ini, but the engine prompts that Nanite/VSM assets require SM6 and refuses to render properly.
  4. Cleared DerivedDataCache, Saved, Intermediate, and Mesa shader cache.