Summoning a lightning bolt doesn't cause a lightning bolt to appear right away, rather, it appears the next time you reload the world!

To reproduce:

1. create a new creative flat world with cheats enabled
2. enter the command /summon lightningbolt ~ ~ ~
3. observe that nothing happens (you should have been hit by lightning)
4. back up a bit (so you can see the bolt on reload)
5. save & quit then reload
6. you should see the bolt strike in front of you on load.

This can be more easily seen by summoning the lightning over flammable blocks or over a mob that changes when struck by lightning. The fire/change won't appear until after reloading the world.

Tested on Samsung Galaxy S6 (SM-G920W8), Android 6.0.1 MCPE 0.15.90.7