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.
We'd like to help. Double check your bell settings for the channel & make sure you've opted-in to receive all notifications & not 'Personalized'. You might want to check your device level notification settings with these steps: https://yt.be/help/AKer . Let us know if that helps.
Best of wishes.