I am assuming that the data was created like this:
That would cause the data to appear as if it was not at the top of the cell.
If that is the case, try these steps:
1. Select the cells that have this problem
2. Ctrl+H to display Find and Replace
3. In the Find What box, type Ctrl+J. Nothing will appear (except maybe a dot). This is the bizarre, unexplainable shortcut key for simulating an Alt+Enter in the Find and Replace box.
4. Leave the Replace With box blank
5. Choose Replace All
You might have to then use Align Top to move the one-line of data (which is not bottom-aligned) to the top of the cell.