Thanks for reaching out. Make sure that you've selected 'Publish to Subscriptions feed and notify subscribers' option before you upload the videos. Also, could you check with your subs, if they've selected "all" notifications instead of "occasional"? Keep us posted.
Thanks for the details. You'll find "publish to subscriptions feed and notify subscribers" option while uploading a video. Let us know if you're still not able to find the option.