The M5Atom library hides its actual includes of sublibraries behind an #ifdef block.
PlatformIO does not evaluate this preprocessor directive by default, like the documentation says.
https://docs.platformio.org/en/latest/projectconf/sections/env/options/library/lib_ldf_mode.html
Since the inclusion is in the header, and not in a source file, I guess also chain+ would work.