Steps to Reproduce:

1. Build this setup
   
2. Fill the dispensers with TNT
3. Stand in the center of the water or spawn a mob in the center
4. Switch to Survival mode if you are standing in the water
5. Activate the dispensers and wait for the TNT to explode

Observed Results:
The player/mob is not launched high into the air.

Expected Results:
The player/mob should be launched high into the air.

Original Description;
Hi

I was playing on a friend's realm on creative, and i build a tnt player launcher, i tested it (i was still in creative) and it worked, it launched me very high, it was succesful; but when i tried it in survival it didnt launched me, i tested it plenty of times because i taught it was like a 50/50 chance, but no, it didnt worked.

The tnt launcher was the common design with dispensers around a 3 by 3 square full of water and a button to activate the 12 dispensers, and of course i was on the middle of the water square...

The problem is that is not working on survival.
I test the same tnt launcher on a local world, a world of my own, and it didnt work either.
So is not the realm.