Your Microsoft Account requires attention to get Insider builds

And you are not able to re-enter your Insider-account to receive new builds? And nothing shows up in Windows Update? I do remember that there were some issues with one previous build due to Microsoft changing the rings in the back-end. However, I do beelive that that were later than the build you are running. Also, because of your build being quiet old, its possible that the upgrade wont work - even though I doubt it. You can always try to remove the PC from the Insider program and re-add it again.