The attach_workspace step relies on tar and gzip in your environment. If you're having trouble with restoring your workspace you may need to update the current versions of gzip/tar or use a different implementation entirely.
You may see this error in the build output:
Using busybox tar, if you run into issues, please try installing GNUtar.
It is known that the versions of tar/gzip that come from BusyBox can result in issues, and reinstalling them on alpine images with apk add --no-cache tar gzip can help resolve problems.