Hi ! If you have configured the right amount of leds in the setup (for instance "16 "for 2x8leds strips), I would say they are DOA indeed, default simhub settings drives 16 RGB leds . You are the third in a couple of weeks having this problem, it looks like some bad quality batchs are sold right now.
For the curious, these leds works as a chain, each led chip sends the signal to the next one, if somehow one led is broken it's all the next leds which won't work anymore.
Wow, you are very fast answering, thanks.
I will try with new ones