Ensure that you are in survival mode and MobGriefing is true
Observe that when a creeper explodes it does not damage and does not create an explosion crater
**this worked perfectly fine in 1.13.2 and when the world was created it was create as a survival server, I haven't installed any mods that should affect this explosion (the creeper is not silenced with a tag)
Not happening for me, creepers explode fine with mobgriefing off!