If you find that hashPrinter is not showing your hashtagged photos on instagram, make sure that any photos and the user profiles that upload them are set to be public. See this post on instagram's website for more information.
After hashprinter has displayed the first set of photos, only newly uploaded photos that are added to instagram will be downloaded and displayed by hashPrinter. It is not possible to force an old photo to display by adding a hashtag to it.
Make sure your computer is not set to go to sleep or standby. This will stop HashPrinter from updating photos after the computer comes back on.
Lastly, make sure you have a solid internet connection throughout your event so photos can be downloaded from the internet.