I have been using the HP Sprocket for almost a year. After about 6 months I had printing issues so I was sent a replacement under warranty. That was in January of this year. The printer was working okay, until recently I updated the HP Sprocket app on my iphone. With the new app "improvements", I have noticed that my printer is now printing repeats. It starts to "cool down" after the 4th image, then if it runs out of paper, then the queue doesn't update and it repeats the last image printed. The last batch of photos I needed to print had more than 6 sheets of duplicates because it was constantly cooling down, then printing multiples, then running out of paper.
The firmware does not need updating. I have tried to "forget" the device on bluetooth, and also uninstalled and reinstalled the app. I do not have issues with my iphone 8. The printer is always at more than 50% battery (I don't take it traveling often), and I always use the HP Sprocket paper. I also used a pin to reset the printer, but nothing changed.
The printer I have is currently out of warranty, so I am stuck with this until it gets fixed, or until I run out of paper and buy another brand.