That’s right — we are already aware of this issue and you can follow along with any progress here:

https://github.com/Automattic/jetpack/issues/10876

In the meantime, a workaround would be to install the Classic Editor plugin. You should then be able to access the previous TinyMCE editor along with the subscriptions option, after that plugin has been activated.

The Classic Editor plugin solution does not work for me. When I add
add_filter( ‘jetpack_allow_per_post_subscriptions’, ‘__return_true’ );
to the theme’s functions.php file the code shows within the dashboard center frame and other parts when navigation admin. Classic editor also does not work then, so I’m never able to see the checkbox per the classic editor. Not sure if it’s working for others but it is not for me.

I have to remove the code from the functions.php to use WP properly. It looks like the issue has been known since Dec 7, 2018, so hope to see a fix shortly.