Formatting and moving files to larger drives in G Tech Tunderbolt

I have a G Tech Thunderbolt with 3 8TB drives configured as raid 1. The computer is a 27" IMac (late 2012) OS 10.12.
I’m upgrading to a 24" IMac OS 14.2. 2TB ssd, and trying to expand from 3 8TB HGTS drives to 3 16TB WD Red Pro drives. I have reformatted the 16’s and tried to move the files from the 8’s by way of configuration and rebuilds to the 16’s.
When the reconfigured and rebuilt 16 is mounted in the G Tech housing by itself, it shows as an 8TB, not as a 16. I was expecting the 16 to show with 8TB of used space and 8TB of empty space ready to be used.
I have erased the 16’s at least 6 times, along with reconfiguration and rebuilds in both the old and new computers, and get the same results. I have made many rebuilds with the 3 8TB drives I’ve been using for the last 6 years. Can someone give meany suggestions on this issue? Thanks

Hi @curtdude

Have you opened a Support Case? If not opened, for more information, please contact the WD Technical Support team for the best assistance and troubleshooting:

I just submitted a case support to WD.
Thanks