This issue seems to me like it could be related to this issue...
I'm going to bet that if you are on a regular monitor the issue goes away but when using a touchscreen you will have the issue. I believe it is related to the touch interface and linux somehow. The extension mentioned in the link seems to fix the issue on Ubuntu by making Ubuntu think a keyboard is always plugged in, so it keeps the OSK disabled. You can then use Ignition's touch screen mode to enable the OSK through Ignition.
It's only an issue when using the touch interface. Even with the touchscreen being used, it works fine as long as I use the keyboard and mouse. It's only when I use the touchscreen that the OSK has these issues.