Unclear to me what’s going on with subscriptions and the feed in general. Have sent a few emails to YouTube. Any ideas @TeamYouTube? https://twitter.com/manuelleaoj/status/976878565651353600 …
These are tricky to troubleshoot as each person likely has a different notification set up, but this is a good resource to pass along: https://goo.gl/cjmQhG . If nothing helps, submit feedback directly from YouTube, thanks!