System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce RTX 2080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 456.71

Blender Version
Broken: version: 2.83.17 Release Candidate, branch: master, commit date: 2021-06-30 07:01, hash: rBc5c4727d6ed7
Worked: (newest version of Blender that worked as expected)

Hi,
doing a particle disk cache and reloading it as an external input on an other scene doesn't seems to work anymore.

• new blender scene
• on the default cube create a default particle system
• save the scene (to bake the particle on disk)
• add a new cache (name it "test")
• activate, in the particle system, disk cache
• bake all dynamics

• open a new blender
• select the default cube
• add a particle system
• save the scene
• add a new cache (name it "test")
• activate, external
• select your previous folder particle bake

and you don't have all the particles

I tested on 2.83 2.93 same wrong result, on 2.70 works perfectly