There’s currently Live Weather lightning located at: 1° 40’ 2.23" N 77° 44’ 15.83" W
The clouds producing it are weak sauce, but it’s there and pretty frequent.
A fairly easy way to find lightning is to click around on the World Map in the tropics (equatorial South America in this case) where there’s some clouds depicted. If you have Live Weather selected in the weather options, you may eventually see the weather icon on the top right of the World screen update to a thunderstorm. Start the flight there.
Then turn on Developer Mode and open the Weather Debug window. Slew around the immediate area until you see the Ambient Thunder Probability go above 0:
The debug window is pretty interesting to follow. There are very small “hot spots” where the lightning is on. Once you fly off of that spot, all lightning is switched off. Even if you see a cloud produce a bolt, and you immediately fly up to the cloud, the lightning will stop if you’re no longer over a “hot spot”. The hot spot has to be over your aircraft and then distant clouds start producing lightning. I never saw any values other than 0% and 1.67%.
There may also be a bug. I saw a couple of hard transitions. After one transition the lightning started, and then after the other one, it stopped until I hit another hot spot. It was like there were conflicting weather sources it was trying to load or something. I don’t think I was close to a METAR area either.