See if she'll start without pulling in the clutch- yes? Not supposed to. That means the clutch switch is not working properly- you may be able to fix it or replace the switch. That switch controls a whole lot of things, one of which is the gas level. Strange, but absolutely true.
You can find photos of the switch apart here and the discussion where I figured this out some years ago on my Roadster....
Here's some late night reading material that came up after some Googling results- after all, this is probably a Triumph thing, not just the Rocket3... https://www.thetriumphforum.com/threads/tiger-1050-fuel-gauge-clutch-switch.17629/...