Loading a valid rootfs.gz created by iSH causes file not found error.

Workflow: 1) Destroy key files needed to boot copy of Alpine~3.8 until it can no longer boot, until boot gives error codes -2 (unable to locate file). 9Gb example fs can be available if required for demo.-purposes.
2) Create a local backup of borked Alpine Linux using iSH filesystem backup tool.
3) Use gzip to test iSH-archived rootfs.gz archive for validity. If compressed file is incomplete/corrupt, recreate from step 2 above. Note: none have yet been found corrupt by me.
4) Use iSH to restore that valid archive which had been created in step 2 and verified in step 3 in order to install it.
5) Failure occurs during early decompression claiming file not found. A video of the output probably could be taken of this step to accurately identify that which cannot be humanly observed.
This error perplexes me because although it seems to halt while looking for a particular file, when I otherwise ask iSH to restore a different file system from any other archive container which was not created by iSH’s backup function, one which I know absolutely doesn’t have the required files to boot, that alien archive is unpacked entirely without any complaint... and (as expected) is never bootable.