If you go to your Hydra Lister Settings --> Settings US is your Sku Grid Remote Key Filled in? Please see the image below. If this is filled in, is it the same as the Sku Grid Remote Key in Sku Grid? This is what links them together and they should be the same.

To check this: In Sku Grid go to Settings --> Remote API look at the remote key that's in the box...is there a key there and is it the same as the one in your hydra lister settings? If it is missing or not the same, you will need to click the button to generate a new sku grid remote key. Highlight and copy it.  Click Save Settings.  Then go back to Hydra Lister Settings and paste in the new Sku Grid Remote Key and save the settings.  Give it some time and your items will start to carry over to sku grid.