Detached Mirrored HD instead of Selecting Offline

Version: TrueNAS-13.0-U6.1


I removed a defective HD using the GUI > Pool > Status and selected the wrong option of “Detach” instead of “Offline”. I added the new HD to the mirror and then realized my mistake. So I ended up adding it (da7) to the mirror and resilvered pool.

However, my pool size has decreased from 14 TB to 10 TB. Any way to reclaim the missing 4TB? I tried running via GUI to “Expand pool” but the new pool size is still 10TB.