Within the web-based mail (also on mobile) my inbox is only showing the last 30 days of emails. There are several hundred that are older than this date that are not displayed. They won't show up in searches, but if I put the email in other folders they will still be there after the 30 days.

If I go into Outlook or Thunderbird these older emails display within my inbox.

I can't find any settings within web based mail and the IT admin couldn't find anything in the backend settings. I'm the only one out of 450+ users with this issue. I've tried Chrome, FF, and IE, all with same problem.