Link to the code that reproduces this issue

https://github.com/mavenskylab/next-15.4-issue

To Reproduce

1. Start next development server
2. navigate to localhost:3000/issues/0
3. Page returns a 404

Current vs. Expected behavior

Current Behaviour:

The page returns a 404 error when navigating to a nested route with dynamic params.

Expected Behaviour:

The page should load correctly for nested dynamic param routes under static locale params.

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 24.4.0: Fri Apr 11 18:33:47 PDT 2025; root:xnu-11417.101.15~117/RELEASE_ARM64_T6030
  Available memory (MB): 18432
  Available CPU cores: 12
Binaries:
  Node: 22.11.0
  npm: 10.9.0
  Yarn: N/A
  pnpm: 9.14.2
Relevant Packages:
  next: 15.4.3 // Latest available version is detected (15.4.3).
  eslint-config-next: N/A
  react: 19.1.0
  react-dom: 19.1.0
  typescript: 5.8.3
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

Dynamic Routes

Which stage(s) are affected? (Select all that apply)

next dev (local)

Additional context

Orignal X Thread

_NEXT-4650