I’ve been using plex server on MPWP for long time with success. I noticed that plex has recently released Plex Media Server version 18.104.22.1683-782228f99 (March 14, 2019). On the page https://www.plex.tv/apps-devices/#modal-devices-wester-digital-mycloud you can MPWP is supported, but the version of the update for this drive is not available (as it is for other WD NAS). at https://www.plex.tv/media-server-downloads/?platform=wd#nas.
Contacted Plex and they mention WD needs to release this for MPWP. When will that happen?