When you use the command: /summon LightningBolt it only displays the lightning from y level 137 and below
Steps to reproduce:
1. set up a hopper clock and trigger this command in a command block: /summon LightningBolt ~ ~1 ~
2. fly to y level 138
3. watch the sky light up but no Lightning appears
Cannot confirm, see screenshot.
At Y=248 and looking straight up