This happens when the number of posting slots available are fewer than the number of products you've selected. To fix this, simply add more posting slots to the plan. Click here to learn how to edit a Marketing Plan.
💡If you already have a sale active on your store and want to promote just those products, you can do so with the Promote Sale option. Click here to find out more.
💡 This is also handy when you want to promote only a few products in your sale. Let's say you have 1000 products on sale, it may not be feasible to promote all of them. In that event you can use the Promote Sale option to create a Marketing Plan with just those products.