@danielclasson your procedure worked perfectly. Thanks for putting all of that information together.
I have begun to play around with HP's Client Management Script Library. It's a (surprisingly) robust set of PowerShell modules for a lot of activities - Softpaq repositories, BIOS/firmware updates, BIOS config baselines and the like. It seems to do a lot of things and do them well.
Still, though, we don't adjust procedures like BIOS updates until we've done significant testing over a period of months. CMSL is worth a test drive for sure, though.
https://ftp.hp.com/pub/caps-softpaq/cmit/hp-cmsl.html