last post / next post link

Hi there –

Post preview in the “Customize” function of the backend shows “last post / next post” links on the bottom of each post as intended. However, when I visit they page from external, the links are not shown underneath the posts… https://www.bastianmathes.com/2016/01/3-toolboxes-to-up-your-strategy-game/.
Any ideas?

Thanks very much.
Bastian