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With your shared workbook, does someone else have it open when you are trying this? Sharing in Excel is still a pretty iffy thing, and if the other has made changes and not saved them (and you can't see them until they have been saved) then Excel is probably waiting to see if there are formatting changes that would affect the sorting - for instance, if you have a conditional format that changes the color to red when a certain value falls below a set number, and the other is entering data that would affect how this is - or is not - colored, then Excel should wait until the calculation(s) are completed.