I also encountered this problem and looked into it.
When I looked at M5Stack's GitHUB repository, I noticed that the F/W version was 2.
My item was 1
https://github.com/m5stack/M5-PbHUB-Internal-FW

After rewriting the F/W, multiple LEDs can now be controlled normally.
It seems there was a problem with the initial F/W.
https://x.com/washishi/status/1840095657954291775

To rewrite, you will need a tool (ST-LINK) that can write to STM32.