In default Magento Version 2.2.7 product listing page category product Position working fine.

If you have customized product collection for list page, then you have to need sorting your collection using Position like addAttributeToSort('position', 'ASC')

Example:

$productCollection = $this->getCategory($categoryId)->getProductCollection()->addAttributeToSelect('*')->addAttributeToSort('position', 'ASC');

Let me know if any query.

Hope it help!

In default Magento Version 2.2.7 product listing page category product Position working fine.

If you have customized product collection for list page, then you have to need sorting your collection using Position like addAttributeToSort('position', 'ASC')

Example:

$productCollection = $this->getCategory($categoryId)->getProductCollection()->addAttributeToSelect('*')->addAttributeToSort('position', 'ASC');