Storage spaces virtual disk not showing physical disk members

I have a SOFS cluster with two servers and two volumes on Server 2012 R2. One of the two volumes does not show any physical disks associated with it via either PowerShell or in Server Manager, although it shows status as healthy and seems to be working fine in all regards.

This volume shows what I would expect:

PS C:\> get-virtualdisk -friendlyname "volume 1" | get-physicaldisk

FriendlyName        CanPool             OperationalStatus   HealthStatus        Usage                              Size
------------        -------             -----------------   ------------        -----                              ----
PhysicalDisk10      False               OK                  Healthy             Auto-Select                   930.75 GB
PhysicalDisk2       False               OK                  Healthy             Auto-Select                   930.75 GB
PhysicalDisk3       False               OK                  Healthy             Auto-Select                   930.75 GB
PhysicalDisk16      False               OK                  Healthy             Auto-Select                     1.82 TB
PhysicalDisk7       False               OK                  Healthy             Auto-Select                   930.75 GB
PhysicalDisk14      False               OK                  Healthy             Auto-Select                   930.75 GB
PhysicalDisk1       False               OK                  Healthy             Auto-Select                   930.75 GB
PhysicalDisk6       False               OK                  Healthy             Auto-Select                   930.75 GB
PhysicalDisk11      False               OK                  Healthy             Auto-Select                   930.75 GB
PhysicalDisk9       False               OK                  Healthy             Auto-Select                   930.75 GB
PhysicalDisk13      False               OK                  Healthy             Auto-Select                   930.75 GB
PhysicalDisk4       False               OK                  Healthy             Auto-Select                   930.75 GB
PhysicalDisk12      False               OK                  Healthy             Auto-Select                   930.75 GB
PhysicalDisk8       False               OK                  Healthy             Auto-Select                   930.75 GB
PhysicalDisk5       False               OK                  Healthy             Auto-Select                   930.75 GB

PS C:\>

But this one, not so. It should be pretty much the same drives as above:

PS C:\> get-virtualdisk -friendlyname "volume 2" | get-physicaldisk
PS C:\>

However, this is interesting, as it seems to know from the other way around:

PS C:\> get-physicaldisk physicaldisk1 | get-virtualdisk

FriendlyName        ResiliencySettingNa OperationalStatus   HealthStatus        IsManualAttach                     Size
                    me
------------        ------------------- -----------------   ------------        --------------                     ----
Volume 2            Mirror              OK                  Healthy             True                               4 TB
Quorum Disk         Mirror              OK                  Healthy             True                               4 GB
Volume 1            Mirror              OK                  Healthy             True                             2.5 TB

PS C:\>

I don't know if this is just a problem with the tools and don't know how to diagnose further. I don't see any event messages that seem interesting with regard to this. I have tried rebooting each SOFS cluster node (one at a time) with no change. The cluster and volumes did fail over and continue to work across the reboots as expected.

Any ideas?