Paul, for what it's worth, I was able to get my hosted data from your first link (had to re-sign into AGOL), The second link just brought up text..
If your accounts are different for GeoNet and AGOL (and the dev login), IE has issues when trying to switch between the two....depending on the order you log in. If already logging into GeoNet, it sometimes tries to use that automatically when switching to AGOL or Dev, which can give an error.
I use Firefox which handles my two logins a bit bette and was able to get into both.r. I don't use Chrome enough to know the normal behavior.
By he way, this is what I saw, after logging in, and then trying your second link...