I had been getting reminders to enter my Outlook password on my iPad for many weeks now (but not on my Samsung phone) but mail was still coming through and going out so I just ignored it. Because I had recently been informed that my email and PW may have been compromised, I updated my Outlook password last night and set up 2-step verification. Sometime this morning I stopped getting mail updates on my iPad Outlook. No issues on my Samsung phone. IPad kept telling me I had to sign in to Outlook but when I clicked on the “sign-in” pop-up it took me to a blank page and I got no further. I tried many of the workarounds posted here, to no avail. I was just on outlook.live on my Samsung and under my account I thought I would turn off 2-step verification and voila! When iPad Outlook again asked me to sign-in it actually took me to a workable sign-in page and once I signed in my emails updated. I will try to replicate this again by turning 2-step back on, but that will have to wait for another day when I’m not so annoyed.