Backing up to Backblaze from Studio

AFAIK, this is usually caused by macOS permissions/security settings on Apple Silicon Macs, rather than the WD drives themselves.

Since you’ve moved from an iMac to a Mac Studio, Backblaze can sometimes show older messaging about third-party kernel extensions / Safe Mode, but in most cases the actual fix is to make sure Backblaze has the correct macOS permissions and that the external drives are mounted in a way Backblaze can track properly.

Please try the following:

Verify that the WD drives are mounted and visible in Finder

• Open Finder and confirm each WD Elements drive appears normally and stays connected.
• These drives should be formatted as APFS, Mac OS Extended (Journaled), or exFAT.
• If the drives are showing and accessible, continue.

Give Backblaze Full Disk Access

• Go to System Settings > Privacy & Security > Full Disk Access
• Make sure Backblaze is enabled
• If you change anything, quit and reopen Backblaze, or restart the Mac

Check whether the external drives are selected for backup

• Open the Backblaze Control Panel / Settings
• Confirm the WD drives are listed and selected to be included in backup
• If they are not appearing there, unplug/reconnect them and reopen Backblaze

Ignore the kernel extension message unless Backblaze specifically confirms it is required

• On newer Macs like the Studio, most backup apps should not need legacy kernel extensions
• If Backblaze support specifically asks for a system extension or reduced security setting, I’d wait for their exact instructions before changing any startup security settings

Restart and re-index

• Restart the Mac with the drives connected
• Open Backblaze again and leave the drives attached for a while so it can re-scan them