Particles are not affected by External Forces when loaded from AssetBundles with Strip Engine Code enabled

Thanks for the detailed repro project and follow-ups.  After investigation, this is working as intended and we will be closing this as Won't Fix.  The behavior you are seeing is a consequence of Managed Code Stripping (Strip Engine Code) interacting with content that lives only in an AssetBundle. When the Particle System (and the  Physics module it relies on for External Forces) is not referenced by anything in the main Player build, the build pipeline does not see a dependency on those modules and strips them.  The AssetBundle is then loaded into a Player where the supporting engine code no longer exists, which is why External Forces silently stop working on device (and why the issue does not  reproduce in the Editor, where nothing is stripped).  This is documented here: Managed code stripping — Preventing module stripping (https://docs.unity3d.com/6000.4/Documentation/Manual/managed-code-stripping-content.html)  ▎ You can't use a link.xml file to prevent entire Unity modules (for example AI or Physics) from being stripped.  ▎  ▎ If you need to use types from a module in an Addressables build, make sure the Player build includes some content that references that module. For example, to keep the Physics module,  ▎ add a component such as a Rigidbody or Collider to a GameObject in a scene included in your build. This creates a dependency that the Player build process recognizes, and preserves  ▎ the module.  Recommended workaround  In a scene included in the Player build, add a GameObject that references the modules used by your AssetBundle content. For this case, that means:  - A Particle System component (to preserve the ParticleSystem module), and  - A Rigidbody or Collider (to preserve the Physics module that External Forces depend on).  The object can be disabled — it just needs to exist in built content so the dependency is visible to the build pipeline. Alternatively, disabling Strip Engine Code in Player Settings  also resolves the issue, at the cost of a larger build.  Thanks again for the report, and apologies for the friction here.

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