Not able to retrain SSD MobileNet V2 FPNLite on GCP AI Platform

Prerequisites

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• I am using the latest TensorFlow Model Garden release and TensorFlow 2.
• I am reporting the issue to the correct repository. (Model Garden official or research directory)
• I checked to make sure that this issue has not already been filed.

So i am currently trying to migrate my former TF 1.15 Object detection API scenario to TF2. I am training all my models on GCP AI platform. So what i have done now is trying the whole thing with TF2. I downloaded the pretrained SSD MobileNet V2 FPNLite 320x320 model from the TF2 repository to use it for my transfer learning. As instructed in the documentation, I cloned the repository and followed the steps to install the object detection api. Then i edited the model config file to fit to my needs. (I just change num_classes, fine_tuning_checkpoint and the path variables to point to my tfrecords) All my artifacts like the tfrecords, config and output dir are stored in a GCP bucket. After this i tried to start the training on GCP AI platform with the following command inside the research folder:

gcloud ai-platform jobs submit training object_detection_`date +%m_%d_%Y_%H_%M_%S` \
    --runtime-version 2.4 \
    --python-version 3.7 \
    --job-dir=gs://${MODEL_DIR} \
    --package-path ./object_detection \
    --module-name object_detection.model_main_tf2 \
    --region us-central1 \
    --config ${PATH_TO_LOCAL_YAML_FILE} \
    -- \
    --model_dir=gs://${MODEL_DIR} \
    --pipeline_config_path=gs://${PIPELINE_CONFIG_PATH}

I also have to mention that i run this command inside a conda environment just like I did with the setup.
After executing the gcloud command, the training is queued up.
Then it takes a while to show up the first logs. Then suddenly the training stops with a bunch of always the same error messages:

"jsonPayload": { "message": "NameError: name 'open' is not defined", "created": 1616860467.038573, "lineno": 328, "pathname": "/runcloudml.py", "levelname": "ERROR" },

"jsonPayload": { "pathname": "/runcloudml.py", "levelname": "ERROR", "lineno": 328, "created": 1616860467.037546, "message": "W0327 15:54:26.939787 140658443433792 util.py:161] Unresolved object in checkpoint: (root).model._feature_extractor._fpn_features_generator.conv_layers.1.1.moving_mean" },

So these kind of errors repeat and repeat until the training jobs gets canceled.
As you can see from the gcloud command, i am using the latest TF2 Object Detection API with TF 2.4 and Python 3.7

Does anyone know how to fix that or has the same problems?