Does the location I am in effect the stock checker ?
Yes! Amazon is a very dynamic platform and employs methods to determine your location and tailor the content displayed to you based on your geographical location obtained by your ISP.
For example, a user using the chrome extension in the Phillipeans will see different seller stock statistics due to the fact some sellers don't sell in that region but are willing to Merchant Fulfill in that region. The same ASIN viewed by someone using the United States ISP will not see the same results as amazon.com will detect the nearest fulfillment center and adjust content.
Note the current workaround to manually change or set the "Delivery zip code" before running stock checker with a zip code near your location. Please follow this guide to change the Delivery zip code.