Mine was turned off for awhile but I turned it back on. Click Youtube profile icon in upper right hand corner, then click little gear settings icon, then notifications on the left. Here is the setting that needs to be checkmarked in order to get sub emails:
I’d like to receive email updates from YouTube about:
General updates, announcements, and videos
x My YouTube channel: updates, announcements, and personalized tips
I think that's the one I changed and then started getting emails again.