In 8.900 I have found the following issue.
Under Site-to-Site VPN >> IPSec >> Local RSA Key under the section
Local RSA key VPN options if you change the option VPN ID Type: to IP Address the option for "VPN ID Type:" with it's drop down menu will disappear and stay gone if you hit apply.
I tested and verified it shows the same with the following browsers
Firefox 10.0.2
Firefox 11
Chrome 17.0.963.79 m
Internet Explorer 9.0.8112.16421 32bit
Internet Explorer 9.0.8112.16421 64bit