I get the same problem on my PUJJOFLEX but with Windows11
Sometimes it gets detected – sometimes it doesnt (especially from cold boot)
I just have to EC Reset (Esc-Refresh-Power) a couple of times and power off/on till emmc + windows boot manager shows up in BIOS as bootable-- then it will boot just fine.
Most likely a coreboot bug or something weird with the PUJJO___Lineup__
– we most likely need to get some output information from our devices (dmsg) for Mrchromebox to see if he can find anything weird with these models.