Indexing: Not including most recent emails (Outlook 2010)

Within the last week, X1 v6.7.4 indexing stopped capturing Outlook emails with a date stamp of 11/29/2012 or later. I checked the Knowledge Base, and didn't find a hard upper limit on the number of items (emails) that could be indexed, only a potential threshold of 1.5 to 2 million items. I'm nowhere close to that threshold.

Indexing on files, on the other hand, continues to work fine, capturing the most recent additions.

Please advise.

---