When I was trying to download the ds004146 BIDS dataset by the chrome browser-based download interface, there were only the json files downloaded, the nii files can not be downloaded.
Same as raamana (Bug in downloading datasets from openneuro), I tried it with an without signing in, the nii files still can bo be downloaded.
Do you get an error message? Can you try another way of downloading (e.g. Git / DataLad)?
I didn’t get any error messages, but they’re only json files in the sub-folders of participants. I can not find any nii files after clicking the download button in the browser.
About the Git and Datalad ways, I have not successfully performed owing to my personal reasons.