This probably wasn't a bug. I experienced the same last week but it was because I ran the backup command from a different directory. I've created a note saying:
first `cd` to the parent directory of the `source_dir` to avoid too many nested directories in the repository and conflicts in the mounting point path (so that the file change detection of restic works when mounting the drive to be backed up at another point)
`restic backup -v -r <location>/<repo_name> <source_dir>`
first `cd` to the parent directory of the `source_dir` to avoid too many nested directories in the repository and conflicts in the mounting point path (so that the file change detection of restic works when mounting the drive to be backed up at another point)