1. When I tried Plus Point Upgrade, Expert Mode details show up, as Hipplewm posted.
2. I then went back to select mileage upgrade, Expert Mode details also show up, as reported in my preceding post.
3. I then logged out and re-logged in, selecting mileage upgrade first, Expert mode details are hidden again, so it seems that the Plus Point upgrade triggered the Expert Mode. Without first selecting Plus Point upgrade, the Mileage upgrade failed to show Expert mode details.
4. I then logged out and logged in once more. This time selecting Plus Point upgrade led to Access Denied
5. Tried log-out and in several times. Got the Plus upgrade to work and show Expert mode details after several tries, but subsequent Mileage upgrade ended in Access Denied.