Same exact problem. I recently purchased Cubase 12 Pro and downloaded all the software directly so that I could avoid running faulty Steinberg Download Assistant (which has the same problem, namely, a useless sign-in button) and now the activation manager is messed up and I’m stuck with four hours wasted on troubleshooting, 600 dollars gone, and no software activation.
I met this too! But I guess there is nothing wrong with you software or sttings but extremely serious delay. I first tried at around 7:00 p.m., now it’s 12:00 p.m. and everything just turn right even without reconnecting net or restart computer. (Well maybe it’s just my personal experience but you can have a try )