This question is about Drupal 8.
Placing the following line inside a story node's body (I guess it also works for other content types) adds a manual teaser break:
In Drupal 7, to make manual teaser breaks work with the "Filtered HTML" text format it was necessary to add
<!--> to the text format's set of allowed HTML tags (for instance, see this "Drupal Answers" post).
In Drupal 8, however, this solution no longer works: Manual teaser breaks are silently ignored even if
<!--> is present in the allowed HTML tags of "Filtered HTML". I have tried to add a couple of plausible seeming combinations to the "Filtered HTML" text format, such as
<!---->, and a couple of implausible combinations (
<!--.*-->), but nothing works.
I double-checked and manual teaser breaks work fine when I switch a story's text format to "Full HTML" text format.
How can I get manual teaser breaks to work again with "Filtered HTML" in Drupal 8? If this is not possible I will have to go through all nodes of my site after the D7 > D8 migration and switch them to "Full HTML".