If your order is not showing as shipped in eBay but it is in your eCommerce store and in our system, then you may not have provided the Tracking ID and the carrier i.e who is delivering the package. These two pieces of information are MANDATORY in order for eBay to update the shipped status. If you do not have a proper tracking ID leave it blank. Do not enter comments or n/a or no or - o. Leave blank if you do not have a proper tracking ID.
When you mark an order as shipped in your eCommerce platform make sure you also complete the tracking ID and the carrier. eBay requires both the tracking ID and the carrier.
Also, if your customer doesn't know both of these they are not able to track the package.