I just uploaded my associate photographers images into Lightroom. I went to sort by capture time and they are all over the place. A picture of the ceremony, then a picture of the reception, then getting ready. I don't know why they would be out of order?
To troubleshot this, make sure that Library grid view is showing the capture time above the thumbnails via View > View Options. Then make sure the tool bar is showing via View > Show Toolbar and you've selected Sort: Capture Time in the toolbar. Finally, post a full-resolution screenshot of your LR window showing the thumbnails out of order. A picture is worth more than a thousand words and will let us avoid playing twenty questions.
To troubleshot this, make sure that Library grid view is showing the capture time above the thumbnails via View > View Options.