There's a couple things you'll want to check to make sure they show as available.
-It can be your fulfillment method that needs to be set up for every item to be available. You can make these edits in your Online Square Store by heading over to Item Library > Click on each Item and scroll down to > Fulfillment > All. There needs to be pickup/delivery options checked for them first.
-Making sure your items are set to > Visible under > Items > Item Library.