I don't know about the 18 tiger, but on my 19 scrambler there are conditions that can disable cruise. Mine was disabled after I had the dealer update the firmware.
The process to re-enable was pretty straight forward once I found it. I believe I just turned the ignition on (just on, but do not start the bike), then ran through the controls that can disable cruise. From memory I think I had to hit the front brake, the rear brake, the clutch, cycle the throttle both directions, then hit the cruise button. I'm sure that isn't exact, but you should be able to find the process online with some searching.