Sometimes, not all products are available for bundling due to Inventory Constraints. Certain products might be temporarily out of stock or in limited supply, making them unavailable for bundling at that moment.
Visibility Settings: Check if the bundles are set to be displayed on the storefront. It's possible that during the creation process, the visibility settings might not have been adjusted to make the bundles visible to customers.
If in the process, inventory of any product in the bundle goes zero, the bundle will be unavailable for the customers.