It turns out the problem is that when you export a report CSV the last digit in the task ID is always ‘0’ in excel - the solution is to import into google sheets - as found here - Some Task IDs are incorrect on CSV Export
It turns out the problem is that when you export a report CSV the last digit in the task ID is always ‘0’ in excel - the solution is to import into google sheets - as found here - Some Task IDs are incorrect on CSV Export