The man page for backup2l says grep is used to filter the list of files
for --get-available, --locate, and --restore.  It even suggests
prepending ' /.*' to the pattern to match only file names.  However, the
script sets shopt -s nullglob, which causes the for loop (on line 930 in
the current testing version) in get_location to not execute its body,
which means the $TMP.left file is not created.

Since this script is bash, rather than /bin/sh, the simple fix is to use
an array for MASK_LIST.  I have attached a patch.

...Marvin