Double Price updating (via the Service and M2E Pro Connector)

Once the Product is added to the Service, its Price updating is automatically disabled in M2E Pro. It is made to prevent double synchronizing of the Price value of the same Product.

If you want your Item to be updated via M2E Pro and not managed by the Repricing Tool, use the Delete Items option to remove it from the Amazon Repricing Service or Disable it to stop dynamic Price changes for it.

The full article you can find here.