Just posting in case someone else has a similar issue.  Updated a system with a StarTech dual mSATA and SATA PCIe card with a Marvell 88se9230 chipset (PEXMSATA3422) from beowulf to chimaera and it dumped out into BusyBox after a reboot.  Card was in JBOD mode so not a RAID issue.  Downloaded the chimaera installer and it didn't see the two disks either.  Reran the beowulf installer just to make sure the card wasn't malfunctioning and the drives were there.  Card has never had a firmware update so gave flashing the latest version a try using a DOS boot USB drive, and the system booted normally.  Firmware link here:
https://www.startech.com/en-us/cards-ad … xmsata3422

Anyway, YMMV, etc. etc.