For Oracle Data Integrator Version 11.1.1.3.0 and later
Start ODI Studio in clear cache mode like this:

-OR-

Ensure ODI Studio instances are closed

Navigate to $ORACLE_HOME/.odi

Delete the "system<version>" folder, with <ODI version> corresponding to your version of ODI.

Example:

Restart ODI Studio —> a A new folder system<version> will be created.