For the latest PT Ultimate 2019, use ReVibe II version 18.8.
Download and install the latest version of iLok License Manager:
https://www.ilok.com/#!license-manager
In iLok License Manager, deactivate ReVibe II (follow the prompts).
Then reactivate ReVibe II (send it from your iLok Account back to your iLok).
Then synchronize your iLok.