Stanley One Hand Mug Thermos 0.47L Cools Down

I got a great deal on the Stanley One Hand Mug Thermos 0.47 liters - Navy Blue! I snagged it at half price during a discount and made sure to register it. I didn't encounter any problems with leaks during the leak test. However, when I tried it, the drink inside had cooled down significantly after just 2 hours, to the point where it barely provided any warmth to my hand. I reached out to Polar Bear Company and received a response after a lengthy 20-day wait. They assured me that everything was in order. It has been a month, and I have yet to receive the product. I believe it's not authentic, and I will personally reach out to Stanley to address this matter.