lvextend command fails with error 'Insufficient suitable contiguous allocatable extents'

Issue

• The lvextend command is failing to extend lvm volume and shows below error messages:

  $ lvextend -L +21G /dev/mapper/vg1-lv1
    Extending logical volume lv1 to 51.00 GiB
    Insufficient suitable contiguous allocatable extents for logical volume lv1: 672 more required
  

  But the volume group vg1 is already having enough of free space (21.12g) to extend above lv:

    VG     Attr   Ext    #PV #LV #SN VSize  VFree  VG UUID                               
    vg1    wz--n- 32.00m   1  21   0 99.78g 21.12g A123Va-12A3-EtMx-Zv5W-xRRS-dMTq-5h1111