Summary:
If you leave and re-enter the world at the exact moment a TNT is about to explode, the TNT will freeze. It becomes an invulnerable entity that stays in the world forever and will never blow up.
Note: This can happen with even just 1 TNT (during testing, I actually reproduced it with only one TNT), but the timing is extremely hard to hit. Using more TNT doesn't change how the bug works, it just makes it much easier to get the timing right.
Steps to reproduce (Manual):
Place a 3x3 platform of TNT.
Quickly light them with flint and steel.
Leave the world at the exact second the first TNT starts to explode.
Join the world again.
Check if any TNT survived. (If all of them exploded, try again. With a 3x3 platform, it usually takes about 5 tries to get the timing right).
Steps to reproduce (Using world file):
Download and import the [mediaInline] file.
Join the world.
Observed results:
An invulnerable TNT entity is created. It did not explode and will never explode.
Expected results:
The TNT should explode properly, either before you leave the world or after you come back.
Video:
Isn’t this a duplicate of MCPE-23686 , just with the appearence having changed? I have encountered this glitch before, and have made a farm for it using nether portals (which is far easier, and doesn’t require reloading the world, by lighting tnt (placed, then activated with redstone), then having precise timings to use a dispenser with flint and steel to create a portal just as the tnt is about to explode).