Can't do Segmentation: CUDA error: device-side assert triggered

Part 1 (2019)
16 
class SegLabelListCustom(SegmentationLabelList):
    def open(self, fn): return open_mask(fn, div=True)

class SegItemListCustom(SegmentationItemList):
    _label_cls = SegLabelListCustom

codes = ['0','1']
src = (SegItemListCustom.from_folder(path_img)
       .random_split_by_pct(valid_pct=0.2, seed=33)
       .label_from_func(get_y_fn, classes=codes))

data = (src.transform(get_transforms(), size=size, tfm_y=True)
        .databunch(bs=bs)
        .normalize(imagenet_stats))

Is it normal for this code to take quite a while to run? I’ve had it running for well over an hour with just 5000 128x128 images in the dataset. Hoping it will work but I’m not sure what’s going on. I only changed the paths.