Well! I'm not sure why, but somehow my Default Keyboard setup was back to the Samsung keyboard (the default). So I guess there was a new version which was updated and after updating, the Default keyboard switchswitch was back to the default.
Editing that one setting and the Hacker's Keyboard was back in business.
The selection of the Default Keyboard on my phone is available from "Settings" > "General Management" > "Language and Input"