Anchor added to custom tag does not scroll page to target.

Steps:

1. Create e.g. folder.
2. In a richtext field add some text.
3. In between the text add a custom tag e.g. youtube.
4. Add anchor to this custom tag.
5. Select some text and add link to the anchor.
6. Publish.
7. In admin view mode and on frontend try to follow the link.

Actual result: Link does not scroll the page to the anchor.
Expected result: Link scrolls the page to the anchor.