When an update is installed it no longer shows as an available update for is installed. No updates should normally be shown when you use Photoshop menu help>update. You should see all products are up to date.. In that pop-up window click on Preferences to see which Adobe Products you machine is set up to look for updates.
i did not install it (the update)
it did disapear
and the update preferences are like yours
Which version of CS6 do you have installed? There are at least three version of Photoshop CS6 that I know exist. The Subscription version its current update version is 13.1.2, The Macintosh perpetual version it current update version is 13.0.6 and the Windows perpetual version its current update version is 126.96.36.199 however the .3 will not show in the popup window for menu Help>About Photoshop or the CS6 splash screen. Also ACR Update 8.4 applies to CS6 ACR 8.2.1 is for Photoshop CC only. You did not state what Update disappears. "This" is no identification, This updated web site also messes up image. View the following image in a new tab or window to see the actual image so its readable.