Are you still having the problem today @munchiebusiness ?
Have you checked that package weight/dimensions are supported by the shipping service you chose?
Have you checked to make sure there are no issues with the buyer's address - missing apartment number, etc?
Are you running into the same problem when you try to buy a label on the eBay app?
If you want an immediate solution instead of troubleshooting you can to go pirateship.com to purchase a USPS or UPS label. You can link your eBay account so it will automatically pull your ebay orders in to pirate, then pirate will send tracking to eBay when the label is purchased.
