I have layout switching shortcut set to be Left Shift + Right Shift. The following situation happens to me fairly often:
1. I start Ubuntu; switching works.
2. I open "Text Entry Settings...", don’t touch anything and close it.
3. Switching stops working (additionally, 3rd level modifier key changes from Caps Lock to Right Alt).
If it matters, I’m using a custom keyboard layout, which I attached. The file specifies two layouts, "English (Artyom)" and "Russian (Artyom)" — I use them both.
ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: indicator-keyboard 0.0.0+13.10.20130924.2-0ubuntu3
ProcVersionSignature: Ubuntu 3.11.0-9.16-generic 3.11.2
Uname: Linux 3.11.0-9-generic i686
NonfreeKernelModules: wl
ApportVersion: 2.12.5-0ubuntu1
Architecture: i386
Date: Thu Oct 3 22:48:48 2013
InstallationDate: Installed on 2012-08-01 (428 days ago)
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release i386 (20120423)
MarkForUpload: True
SourcePackage: indicator-keyboard
UpgradeStatus: Upgraded to saucy on 2013-10-02 (1 days ago)
It might be related: sometimes layout switching works from English to Russian, but not in the other direction (I have to switch manually through the indicator menu).