How to test the semantic segmentation results of TF version RandLA-Net in Open3D-ML?

### Checklist

- [X] I have searched for [similar issues](https://github.com/isl-org/Open3D-ML/issues).
- [X] I have tested with the [latest development wheel](http://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [X] I have checked the [release documentation](http://www.open3d.org/docs/release/) and the [latest documentation](http://www.open3d.org/docs/latest/) (for `master` branch).

### My Question

I have run the training code of RandLANet with TF version on Paris Lille dataset with the command:
python scripts/run_pipeline.py tf -c ml3d/configs/randlanet_parislille3d.yml --dataset.dataset_path dataset/Paris-Lille-3D --pipeline SemanticSegmentation --dataset.use_cache True --num_workers 0
Which command to test the semantic segmentation results of RandLANet on Paris Lille dataset? I have tested with the following command, but get the wrong results.
python scripts/run_pipeline.py tf -c ml3d/configs/randlanet_parislille3d.yml --split test --dataset.dataset_path dataset/Paris-Lille-3D --pipeline SemanticSegmentation --dataset.use_cache True --num_workers 0

What's the problem? Thanks in advance.

Started testing
running inference
Accuracy : [0.6033437, nan, nan, nan, nan, nan, nan, nan, nan, 0.6033437]
IoU : [0.6033437, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.06703818888888889]
running inference
Accuracy : [0.563903, nan, nan, nan, nan, nan, nan, nan, nan, 0.563903]
IoU : [0.563903, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0626558888888889]
running inference
Accuracy : [0.6278404, nan, nan, nan, nan, nan, nan, nan, nan, 0.6278404]
IoU : [0.6278404, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.06976004444444445]
Per class Accuracy : [nan, nan, nan, nan, nan, nan, nan, nan, nan]
Per class IOUs : [nan, nan, nan, nan, nan, nan, nan, nan, nan]
Overall Accuracy : nan
Overall IOU : nan