RN314 storage not expanding

Hello,

I'm having an issue I was hoping someone could help shed some light on.

I have an RN314 NAS. Previously, I had 4 4TB WD drives installed for a total of about 12TB of storage in a RAID-5 configuration. I recently upgraded all of the drives one at a time to 12TB Seagate drives, but my total storage capacity shows as only 25.45TB. Shouldn't it be 32.73TB? I have rebooted the NAS several times and even re-installed the firmware and made sure I'm on the latest version. Am I missing something?

Thanks