do not use hub but do reboot between two successive installs
hub will provide power (even unpowered hub) for testing but not enough for stable operation, which must be negotiated.
eventually i stopped getting errors about pre-load etc from
sudo kextutil -tn /Library/Extensions/SiLabsUSBDriver.kext
A USB key with a Trinket M0 heart and four RGB NeoPixels for customizable glow.