Hey there, @psco
Bo here from Shopify Support!
As this is your first post in the Shopify Community I would like to welcome you! Welcome! I would recommend reading our guide on getting support from the Shopify Community here so you are best equipped when looking for support through these forum boards.
It sounds as though you may be using the old method of adding items to your dropdown menu. Try the following and let me know how you get on:
#in the Link field when you add the menu item.
You can also watch this video which goes through all the necessary steps:
Before you launch your store I would recommend reading my Buyer Trust 101 guide before launching to make sure that you are not missing anything before bringing customers to your store. We also have this essential launch checklist which is super useful.
Let me know how this goes and if there is anything else I can assist you with, I'm happy to help!
All the Best,