Tflite Conversion not supported for mask_rcnn_inception_resnet_v2_1024x1024_coco17_gpu-8?

1. The entire URL of the file you are using

http://download.tensorflow.org/models/object_detection/tf2/20200711/mask_rcnn_inception_resnet_v2_1024x1024_coco17_gpu-8.tar.gz

2. Describe the bug

According to TensorFlow this model should be able to be converted to Tflite but when I am using the sample Google Colab provided to convert it and I add in the mask_rcnn model, I get this bug.

3. Steps to reproduce

Steps to reproduce the behavior.
https://colab.research.google.com/github/tensorflow/models/blob/master/research/object_detection/colab_tutorials/convert_odt_model_to_TFLite.ipynb
Swapped the model in the notebook with the mask_rcnn model http://download.tensorflow.org/models/object_detection/tf2/20200711/mask_rcnn_inception_resnet_v2_1024x1024_coco17_gpu-8.tar.gz
This model comes from this list https://github.com/tensorflow/models/blob/master/research/object_detection/g3doc/tf2_detection_zoo.md.

4. Possible Causes

I'm thinking maybe the models/research/object_detection/export_tflite_graph_tf2.py on the Tensor Flow Github has not been updated yet?

Thank you for your help.