Magento – Stock is not updating after update the product quantity Magento 2.x

I was having the same exact issue. It seems to have something to do with the server configurations not applying the JS correctly. Knockout JS was attempting load the templates for the admin data grids, but the tags weren't being rendered, now allowing the columns to be counted when it reaches the toolbar.js file.

Solution

Go to your Magento Root and add this to your .htaccess file:

<IfModule pagespeed_module>
    ModPagespeed off
</IfModule>

Doing something that would cast it to a string also does this for you.

E.g. trim the value.

$product
    ->setSku(trim($exportProduct->sku))
    ->setName(trim($exportProduct->name));