Check, in order:

• Active toggle - the group must be switched on in the Menu Groups table; only one group per position is active, so activating a new group deactivates the previous one.
• Position - a Footer group never renders in the header and vice versa.
• Page assignment - if another group is assigned to that page via Show on pages, it wins on that page.
• Empty group - a group with no links renders nothing; add items and save the order.
• Kitchen - groups are created for the kitchen selected when you built them.
• Theme - the storefront header is rendered by the theme's navigation template using the active group for that position; if links still don't appear after checking the above, contact Sprwt support, since some themes have navigation options that are only editable by Sprwt during onboarding.