Thanks for your patience, the 500 error is now fixed!https://twitter.com/TeamYouTube/status/980889488531521536 …
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FYI youtubes notifications still don't always come through even with the bell on. It's not a recent problem. Been like this since they introduced it.
FYI, the notification bell has priority levels. People just content with the first one. And FYI, notifications overshadow one another.
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