Eclipse IDE Ctrl + Backspace not working

I faced the same issue with a fresh installation of Eclipse 4.9 on Ubuntu 18.04 LTS.

I noticed that not only Ctrl+Backspace did not work, but in fact a lot more, e.g. Ctrl+Delete or Ctrl+->/<-.

It seems that this issue is caused by a bug in the Eclipse's welcome screen. To resolve the issue follow these steps:

1. Restart Eclipse.
2. Uncheck "Always show Welcome at start up" in the bottom right corner.
3. Restart Eclipse.

This question and answer on SO led me to the right direction.