Problem solved:
Since this used to work, I started poking around looking at version numbers. It turns out that at some point, the component manager "upgraded" my component from V0.1.16 to 0.2.6. I am talking about: https://github.com/m5stack/M5GFX.git
Sure enough, rolling back to 0.1.16 solved the issue.
I think I am done with automated component management.