Are you losing records, or are they just not exporting?
If just not exporting, you may have the "Group By" box checked in the export dialogue, which, I believe will export only one record of that field choice.
The records are "lost" during the export into the Excel document.
I think you are correct that I have the "Group By" box checked. I assumed this referred to alpha order.
Yeah, happened to me once too. The labeling is not clear.