Portworx node in Kuberenetes has status "StorageDown"

We are using 4 Portworx nodes in Kubernetes, some time ago one has changed status to Online (StorageDown). What does this mean and how to fix this issue? Kubernetes cluster is in IBM Cloud

Ivan_Puzyrny1@cloudshell:~$ kubectl exec portworx-cwttl -it -n kube-system  -- /opt/pwx/bin/pxctl status
Status: PX is operational
License: PX-Enterprise IBM Cloud (expires in 796 days)
Node ID: ed15c634-997d-4beb-b914-b8934ff94825
        IP: 10.187.152.137 
        Local Storage Pool: 1 pool
        POOL    IO_PRIORITY     RAID_LEVEL      USABLE  USED    STATUS  ZONE    REGION
        0       HIGH            raid0           21 TiB  13 TiB  Online  dal13   us-south
        Local Storage Devices: 6 devices
        Device  Path            Media Type              Size            Last-Scan
        0:1     /dev/sdh1       STORAGE_MEDIUM_SSD      3.5 TiB         28 Jan 22 15:40 UTC
        0:2     /dev/sdc1       STORAGE_MEDIUM_SSD      3.5 TiB         28 Jan 22 15:40 UTC
        0:3     /dev/sdd1       STORAGE_MEDIUM_SSD      3.5 TiB         28 Jan 22 15:40 UTC
        0:4     /dev/sde1       STORAGE_MEDIUM_SSD      3.5 TiB         28 Jan 22 15:40 UTC
        0:5     /dev/sdf1       STORAGE_MEDIUM_SSD      3.5 TiB         28 Jan 22 15:40 UTC
        0:6     /dev/sdg1       STORAGE_MEDIUM_SSD      3.5 TiB         28 Jan 22 15:40 UTC
        * Internal kvdb on this node is sharing this storage device /dev/sdf1  to store its data.
        total           -       21 TiB
        Cache Devices:
         * No cache devices
Cluster Summary
        Cluster ID: pw-elastic-data
        Cluster UUID: 88883914-8aec-48f7-9aa2-206d52ad9800
        Scheduler: kubernetes
        Nodes: 4 node(s) with storage (3 online)
        IP              ID                                      SchedulerNodeName       Auth            StorageNode     Used    Capacity        Status                  StorageStatus   Version         Kernel                  OS
        10.187.152.137  ed15c634-997d-4beb-b914-b8934ff94825    10.187.152.137          Disabled        Yes             13 TiB  21 TiB          Online                  Up (This node)  2.7.2.0-1408b62 4.15.0-154-generic      Ubuntu 18.04.5 LTS
        10.187.152.188  9b038895-1fad-4de1-bd46-42f73fa8c85f    10.187.152.188          Disabled        Yes             12 TiB  21 TiB          Online                  Up              2.7.2.0-1408b62 4.15.0-154-generic      Ubuntu 18.04.5 LTS
        10.187.152.236  60066ffa-6805-4ba5-8ba0-a571e0474c5a    10.187.152.236          Disabled        Yes             0 B     0 B             Online (StorageDown)    Full or Offline 2.7.2.0-1408b62 4.15.0-156-generic      Ubuntu 18.04.6 LTS
        10.187.152.212  57b8ca05-8d39-4971-b06f-f95212b26880    10.187.152.212          Disabled        Yes             17 TiB  21 TiB          Online                  Up              2.7.2.0-1408b62 4.15.0-154-generic      Ubuntu 18.04.5 LTS
        Warnings: 
                 WARNING: Internal Kvdb is not using dedicated drive on nodes [10.187.152.212 10.187.152.137 10.187.152.188]. This configuration is not recommended for production clusters.
Global Storage Pool
        Total Used      :  42 TiB
        Total Capacity  :  63 TiB