Yes. After some debugging I realized that paths that contained the input and target images were out of order, so the the original image wasn’t being compared to the corresponding mask. I sorted the lists, and so far I don’t see the error, but the training step is still running. Actually it’s been running for a few hours now, which I guess it’s a good sign, but I was wondering how long finetuning is supposed to take when I have around 500 images in my data set, a batch size of 2, 14 epochs and running on GPU?