RGBA convert_mode not working

I want to create a dataloader with RGBA images. I have set convert_mode as ‘RGBA’ but still, batch contains images with three channels only. I’m using the following code -

dblock = DataBlock(blocks=(ImageBlock, MaskBlock),
                   splitter = RandomSplitter(valid_pct=0.1),          # Random 10% as validation set

dls = dblock.dataloaders(Path('images_with_alpha'), bs=1, num_workers=2, convert_mode='RGBA')
batch = dls.one_batch()

It is giving shape ((1, 3, 400, 280) but I expect it to be (1, 4, 400, 280).

Can you please tell me what’s problem in my code?

This may help, not sure if they solved it but it may give you some hints on solving your issue?