It could be a missing dependency and if you consider the following you may find what that is.
When you flash firmware, it's a good idea to go through and do all the firmwares.
Also a good idea to read the release notes for said firmwares to look for:
- firmware dependencies of other controllers / HBAs / motherboard
- order of flashing - you might need to flash the HBA before you apply this firmware - or the BIOS?
So, when I want to flash RAID controller firmware, I download all the firmwares and read the release notes first. Then, when I am happy that I know the dependencies and there are no conflicts, I proceed.
You might find the device is visible if the dependent firmwares are compliant.