Explosions in Bubble Columns Kill Players, but not Blocks

In Bedrock Windows 10, I wanted to create an Elytra launcher using a bubble column to quickly shoot me upwards, and a timed TNT block which would explode underneath me just as I reached the top few blocks, and hopefully accelerate my momentum.

It worked, incredibly well! I was even able to iterate on the elevator design.

However, upon switching to survival mode and trying the elevator, I would be consistently killed by the TNT, while the structure itself was unharmed.

I tried converting the last few blocks of the elevator to water source blocks using buttons as well, but the TNT still killed me.

My design is a bubble column 31 blocks high encased in glass, with 3 dispensers filled with tnt replacing the bottom 3 blocks.