I assume the cells in column A have data in them. If so then you can use the following code:
One issue I think you were running into was the your code RGB(255, 255, 255) is not the same as no fill.
If the cells in Column A don't have data then the line
will return 1 for LastRow.
I'm not sure how to get the last highlighted cell in a range vs. the last cell with data. In this case you may have to loop through every cell in column A which might take a while. Maybe someone else has some code to get the last highlighted cell.
I have attached a sample workbook.
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