Tom, for what it's worth, on my PC I went to the link in Daniel Yaw Jr. mentioned above. I used the pull-down in the upper left and used "my account" to make sure I was logged into the UC, then selected the UC...selected my planner, and one of the days I know I had something in, and it was there.
Actually, after I saw it all coming up (what I did earlier this week on the PC and from mobile...all sync'd), I wanted to capture the above, so I decided to log out and try it again, and when I selected my account, I got this before I hit the logout button.
Which is incorrect, since I am a registered attendee....so that is strange. I think this is just an incorrect message, since usually you have to be registered to even use the myPlanner option. FWIW, They did fix the issue with having two tabs for speakers on this tab.
Anyway Tom, might be worth a few minutes to try again. I hadn't book marked it, so I used Daniel's link. But my guess is esri took it off the main UC page because they are trying to fix a few things. Another interesting thing about the link, if you do it on a mobile device, it gives you the option to grab it from the devices "store", or go to the mobile's browser version, which also seems to work.