I can confirm I am still experiencing this exact issue and have been for the last few years. After attempting to sign in with a Microsoft Account, I am returned to the main page of the Feedback Site still not signed in. This issue persists across all devices and browsers I have attempted with.
The Microsoft Account I am using does show the Feedback Site as an external app I have successfully given access.
[media]I remember 1.13 was the first time I really noticed this issue, and it seems to generally have gotten worse with each update. 1.18.2 seems slightly improved in some cases when compared to 1.18.1, though.
@kcobb0807, I'm having the exact same issue. I'm not the Realm owner, but everyone else in the Realm can write on signs, chat, and see each other's messages. They cannot see anything I type in chat and my messages on signs disappear when I place them.