Why are my LVM volumes missing, status shown as "unknown", after creating a partition table?

Issue

• Why are my LVM volumes missing after creating a partition table?
• My LVM Physical Volumes (PVs), Volume Groups (VGs), and Logical Volumes (LVs) cannot be found.

• One physical volume /dev/sdX is listed as "unknown device" even though it appears in /proc/partions:

  # lvs -a -o +devices
    Couldn't find device with uuid aaaaaa-bbbb-cccc-dddd-eeee-ffff-gggggg.
    LV                 VG        Attr   LSize  Origin Snap%  Move Log Copy%  Convert Devices             
    lv_root            localvg00 -wi-ao  4.00G                                       /dev/sda2(512)      
    lv_data            localvg00 -wi-ao 40.00G                                       unknown device(0)    <----
  
  # grep sdX /proc/partitions 
     8    16   49283072 sdX
     8    17   49283040 sdX1
  

• I get the following error when trying to restore LVM metadata on a Physical Volume:

  Can't open /dev/sdX exclusively. Mounted filesystem?