Importing a GTFL through the GLTF Datasmith import references incorrect instance meshes when their names contain a period. Which is very common when exporting from Blender which automatically adds the .000 etc. suffix to any duplication or instancing.
Found in 4.22 CL# 6574378
The imported file should have 2 cubes but instead only has one in the scene, however the second cube is still imported
Both cubes would be imported correctly
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-75506 in the post.