When Request Types are configured to appear on an External Client portal, they will appear in the Take Action widget on the Landing Experience.
Things to check
No company overrides on the Request Type Overrides screen
On the Request Type Details screen
Inactive checkbox is NOT ticked
Available For field is set to <External Clients> or <Both>
Uses Status Model checkbox is NOT ticked (This applies only to request types appearing on the Landing Experience and is not applicable to request types on the HR/Business Portal)