Am I missing something in World Star-9?

I’m stuck on a part of World Star-9 in Super Mario 3D World where you ride a platform on rails and have to shoot red blocks to turn them blue.

What’s confusing me is that my shots often don’t seem to register when I fire from the platform. But if I jump off toward the block and shoot in mid-air, it works.

Is that actually intended, like are you supposed to sacrifice a life just to activate that block, or is this just a bug? Has anyone else run into this?