@mikehenson thanks a lot! I haven't been able to find the "new" package lists, but thanks to your post I just messed around with the mirror lists, updating them a couple of times, and now suddenly the system update seems to run smoothly.
Thanks!
Edit: to be exact, forcing an update with the extra "y" in sudo pacman -Syyu is probably what did the trick for me.
Thanks!
Edit: to be exact, forcing an update with the extra "y" in sudo pacman -Syyu is probably what did the trick for me.