After upgrading from Eclipse Neon to Oxygen I noticed that I can no longer navigate around the code by clicking on definitions while holding the Ctrl key down. The indexer itself works fine, and I can still jump around by pressing F3 or using the context menu.
I am using Eclipse CDT with C++.
The following screenshot proves that the feature is enabled.
What am I missing?
You're probably running into bug 517610. Note the following workaround from the bug:
To work around the problem, you can disable the Change Log hyperlink by going to Window > Preferences > General > Editors > Text Editors > Hyperlinking, then untick "Changelog Detector".