There are 4 reasons in this case:
The product is out of stock on the supplier's website
In the Catalog settings, you can choose what to do with the products/variants that have 0 quantity. If you wish to upload these products, you set it as 'Upload with 0 quantity'.
2. The supplier did not approve your request yet
In our app, the suppliers can select who can have access to their products.
For further info about the approval process, you can visit the following Help Center link:
3. You have deleted Syncee from your store, and then you have tried to upload the products. Please make sure that in your Shopify Store, you can see Syncee in the Apps menu.
4. You do not have the appropriate subscription
We only upload the number of products you have in your plan.
For example, if you have subscribed to our free Starter marketplace plan, which allows you to manage 25 products and you are trying to upload 50 products, we will only upload 25.
When you have reached the limit either with your Marketplace or DataFeed plan, you will see the following: