Try looking in your BIOS settings for a setting to “Enable Option ROMs” that would need to be enabled for the HBA firmware to load at boot.
Another thing you could try is to Disable “Quick Boot” or “Fast Boot” or similar which might skip Option ROMs even if they are enabled.
I’m not sure, but the fact that you see all the individual disks in the OS might mean that your card is flashed to IT mode instead of functioning as a hardware RAID controller. IMHO this is actually a better set up; These days Software Raid tends to be better than hardware RAID in just about every way. Both in terms of performance and especially features.
Finally I think it is correct that the 12TB drive is showing up as 10.7 TB. It is likely that the drive is labeled in Terabytes (TB) but the OS is reporting Tebibytes (TiB). This is common. They are the same amount of space but the drive manufacturers use the bigger number for marketing purposes.
If that is not the case and the OS is reporting Terabytes another possibility is that the drive has 4k physical sectors but is formatted 512e using 512 byte logical sectors. That causes some amount of disk space to be unavailable to the OS. You might be able to update that but the fix is complicated and might brick your drives.