Problem adding 2nd HD to Vostro 3020 SFF desktop. Won't boot when connected.

Adding a 2nd hard drive (WD blue, 4TB) to my Dell Vostro 3020 Small Form Format (circa 2023) desktop, running Win11 (well, trying to…). PC won't boot with new drive connected. If I interrupt the startup and look at BIOS setup, the drive is there on SATA-3 but shows 0GB for “type” and no device name. Boot mode is UEFI, UEFI Network stack set to “auto enabled”, HTTPS boot set to “Auto Mode”. New HD has power, I can hear/feel it spinning. I do not have access to a 2nd PC at home to test the HD on another system. BIOS is up to date. RAID mode on. “Secure Boot” enabled, “deployed mode”. Boot sequence set to (1) Windows Boot Manager, (2) UEFI HHTPs Boot, (3) Internal SSD (UEFI RST BC901 NvMe…), (4) onboard NIC (IPV4), (5) onboard NIC (IPV6).

I have tried:

• Both available SATA cables (0 and 3)
• Changing the boot order so the internal SSD is first
• Disabling Secure Boot
• Clearing CMOS
• Changing Fastboot from “thorough” to “minimal”
• Changing SATA Operation in BIOS from RAID to AHCI (does not boot with or without 2nd HD connected)
• “Hot plugging” the drive by plugging it in after the PC booted, New HD not recognized in “system>storage>disk & volumes”, nor “device manager scan for new hardware” nor “disk management”).

Any thoughts on next steps?