Mask rcnn training - whole bounding box is masked

System information

• What is the top-level directory of the model you are using: Object detection
• Have I written custom code (as opposed to using a stock example script provided in TensorFlow): tf_record generated differently via tf record from a blog
• OS Platform and Distribution (e.g., Linux Ubuntu 16.04): MacOS Mojave
• TensorFlow installed from (source or binary): binary
• TensorFlow version (use command below): 1.12.0
• Bazel version (if compiling from source):
• CUDA/cuDNN version:
• GPU model and memory: CPU. 16GB ram (but using Google Cloud)
• Exact command to reproduce:

Problem description

I have successfully created an custom object detection model with this api before. Now I'm trying to train a mask rcnn model but when I look in tensorboard the mask just covers the whole bounding box with no shape whatsoever, like this:

After like 1500 steps no shape at all. I am using the 'mask_rcnn_resnet101_astrous_coco.config' and download the corresponding model to train from. I labeled the images using Rectlabel which generates a xml with bounding box and a mask png. Maybe it doesn't fully accept the png format?

Things I've already checked for:

• set only_faces: False when creating tf records
• I have checked the tf records and it contains a png coded mask 'image/object/mask' (1 example)
• added "metrics_set: "coco_mask_metrics" to "eval_config"
• added mask_type: PNG_MASKS to both train and eval reader

Possible causes:

• I am doing a test with just 37 images to see if it generates a segmentation prediction

At this point I really don't know what to do anymore, so any input or suggestion is appreciated.

This is the tutorial I used: https://towardsdatascience.com/building-a-custom-mask-rcnn-model-with-tensorflow-object-detection-952f5b0c7ab4