Hi there. Just to confirm, have you selected 'Publish to Subscriptions feed and notify subscribers' option before you upload the video? Also, ask your subs to check their device level notification settings with these steps: https://yt.be/help/AKer . Let us know if that helps.
Hmm, double check your bell settings for the channel and make sure you've opted-in to receive all notifications and not just "occassional". Let us know if things still aren't working!