Tensorflow Returning "ValueError: ‘outputs’ must be defined before the loop"

Hey everyone, I hope you are having a fabulous day!

I am trying to train a ResNet50 model on a dataset represented by a tensorflow.python.keras.utils.data_utils.Sequence that I created. When I run the code, I keep getting errors saying that my dataset/generator is returning Nones instead of images and I would really like some help figuring out why and how to fix it.

I posted the issue on Stack Overflow, which seems unusually quiet.

Could you guys please help me out?

Thanks a bunch for your time and efforts in advance!