The issue has been identified and a fix is being implemented.
Posted May 27, 2021 - 09:24 CEST
Update
It is possible you see an error when opening an Excel export file. When you click on OK (or Yes) the file will open. When you use Microsoft Office you can prevent the error by changing the user settings via the username > my Exact Online > user settings. At the section Export you can choose the option Microsoft Office as answer to the question 'Which office software are you using?'.
Of course we are working hard to solve this error when you are not using Microsoft Office. We apologize for the inconvenience.
Posted May 26, 2021 - 10:42 CEST
Update
There is a workaround. Instead of saving the downloaded Excel file, open it directly to acces the data. In case of transactions, click search first and then export.