Update: I think it was a file or a error on some registry, as I had to completely uninstall, restart and then install from scratch to get it to work again.
What I hadn't noticed is that now the download client was automatically updated from version 2.2.0.620 to 2.2.0.717 when I ran it, which it hadn't done before when I reinstalled it.
Sadly I lost a reward of day 1.