Hi,
It’s strange that the [https://pcsupport.lenovo.com/no/en/products/laptops-and-netbooks/100-series/100-14iby/80mh/parts/display/compatible|parts list] for the laptop only shows 2GB and 4GB DDR3L 1600 modules and not an 8GB module. {click on ''Select Commodity > Memory (9)''}
Either it only supports up to 4GB or if it does support 8GB then you may have to try another module in case the one you have is faulty or somehow not compatible with the laptop.