Hello, so my friend also had the same problem on his lenovo pc, not just when hosting bd3 but also in other games too. After he decided to uninstall all of the lenovo pre-downloaded programs on his pc (legion arena, lenovo vantage, and one other lenovo program) the problem just went away. I'm not very well verse in this but we assumed that at least one of the programs were somehow interfering with the upload. Perhaps this is also the issue for your laptop. Hope it helps.
tldr; just uninstall all the lenovo programs on your laptop.
