Asset system files (using the `.asset.blend` extension) are special and cannot be edited like normal files. Opening them showes warnings about this. So better not "encourage" editing these files that much. Note that this check will result in false positives, since users may create files with this extension. Asset system files have an extra flag stored identifying them. Accessing that from the asset representation is a bit more involved, probably requires changes in the asset indexer. For now keeping it simple, the false positives are not a big deal for this convenience operator. Pull Request: https://projects.blender.org/blender/blender/pulls/123781 Part of the brush assets project, see: - https://projects.blender.org/blender/blender/issues/116337 - https://projects.blender.org/blender/blender/pulls/106303