I updated the Xcode extension to 0.33.7 but I noticed it disappeared from Xcode 9.2. When I go to System Preferences | Extensions there is no Xcode section as in the past:

I tried 0.33.6 but same result, not showing in Extensions. I am running macOS 10.13.4 (17E202).
Any ideas?
I have the same issue.
I think it disappeared when I changed Xcode version.
I have 4 versions of Xcode installed: 7.3.1, 8.3.3, 9.4.1, 10-beta 2.
It worked with Xcode 10 beta 1 but disappeared when I installed beta 2 I think (or maybe it was after upgrading to Xcode 9.4.1)?
OK I found a workaround.
My Xcode versioned was named: Xcode-9.4.1.app
I renamed it to Xcode and the menu appeared again.
I have a requirement for multiple versions of Xcode and therefore always name my Xcode applications Xcode-X.Y.Z.app.
I was able to resolve this issue (of the Extension not appearing) _without having to rename Xcode_ by running the following two commands:
/System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -f /Applications/Xcode-X.Y.Z.app
/System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -f /Applications/SwiftFormat\ for\ Xcode.app
Hope this might help. I got the inspiration from issue #422
Most helpful comment
I have a requirement for multiple versions of Xcode and therefore always name my Xcode applications
Xcode-X.Y.Z.app.I was able to resolve this issue (of the Extension not appearing) _without having to rename Xcode_ by running the following two commands:
/System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -f /Applications/Xcode-X.Y.Z.app/System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -f /Applications/SwiftFormat\ for\ Xcode.appHope this might help. I got the inspiration from issue #422