Linkedin has rolled out a subtle but important change to the groups. When you go to the JOBS section of any group on Linkedin, you now only see Paid Linkedin Jobs, the free jobs are now in subtab (Career discussions). This would dramatically drop the views your Free job post get on Linkedin groups.
Not a surprising move by Linkedin to drive customers to pay for the job posting. If you started your group on Linkedin, now you have less control of it (they did not even notify the group creators about this change, quietly rolled it out)