If you can, I’d suggest to leave the relevant file unopened and unaccessed for a couple of days (e.g. over the weekend) with Smartware active and see if that allows it to add it to the backup. This kind of thing is not unknown to happen, especially on larger files (often video files for example) and usually resolves itself with a bit of patience. Hence it’s better to eliminate it first before trying to look more deeply into whty that specific file may not be backing up.
Another alternative may be to make a manual copy (duplicate) of it and put it somewhere else where it won’t get accessed at all and then see if that file copy backs up or not.
