Yes, having more complete information would help prevent some people asking questions. RAID-Zx expansion likely needs some GUI work, its still a new feature. Perhaps report it via “Report a Bug” at the top of the forum pages.
My earlier responses included a comment about WD Red web page issues. Checking again today, I find no reference to WD Red under NAS drives. We have WD Red Plus and Pro, no plain WD Reds. Nor does a Google or WD web page search find the WD Red HDDs, (only the NVMe & SATA SSD). Weird.