Configuring Babel source maps with AVA.

I am using`c8` on top of `AVA` that uses `babel` to transpile the sources on the fly. Is it expected that `sourceMaps: "inline"` works but `sourceMaps: true` does not? In the sense that the coverage reports are correct with the first, and incorrect with the second. Same issue when using `nyc` instead of `c8`. Perhaps it would work without inline source maps if there was an intermediate step generating `.js` and `.map` files on disk. Would `ava` be responsible to make this seamless?