The bug

If an exploding entity, like a creeper or TNT, is on top of a non-solid block with high blast resistance, like an ender chest or end portal frame, its explosion will not destroy any surrounding blocks. What is expected to happen is the explosion damages surrounding blocks just as if the exploding entity were on any other solid blast-resistant block like obsidian.

This could be happening because the explosion originates from "inside" of the blast-resistant block, which blocks it from exiting.

How to reproduce

1. Place an ender chest down
2. Spawn a creeper on top of the ender chest
3. Let the creeper explode or ignite it manually with flint and steel
4. Blocks placed around the creeper, even above the ender chest, won't be damaged