The Western Digital "Red Pro (8 TB, 3.5", CMR)" hard drive is not officially compatible with the Synology DS224+ NAS, according to Synology's stricter compatibility guidelines for their newer models.
Synology has introduced a more restrictive storage media compatibility policy in its newer models, including the DS224+, which primarily recommends the use of Synology's own storage media and restricts support for non-Synology media such as the WD Red Pro hard drives.