Fipaphi Hi
For anchor based - "One page menu" functionality to work in zengrid framework, You may kindly ensure that you have some module published which have been assigned for specific module positions > specific blocks for which menu name have been added in template > framework settings > menus > one page
Example for demo purposes:
I have published module titled SL-Zent assigned to banner module position and Outsider Art in Nederland (NL) assigned to grid5 module position and the menu items in reference are being shown. Ref: Screenshot
Similarly, You may add menu names for specific blocks under framework settings and publish the modules simultaneously for menu items to appear