Hello, so you can try to set the Level file reference to the .uasset file ( the prefab ) and save that. You can find this by double-clicking the prefab .uasset file. This will ensure any custom textures, meshes are using the one in the Level. If you don’t do this, it will not load, it will only show original Fortnite assets. One other thing, I would not use the Other folder, instead copy the .uasset file from the _INT folder and place it somewhere on your content folders and use that. Using the “Content/Assets/Props/Other/myProp” is not reliable, avoid. Hope that makes sense and fixes your issue.
For more details on creating playsets go here:
Good luck!