Thanks for your quick reply!
I checked again and you’re right: The first 991 rows are empty, but there is data below that. Sorry, I didn’t scroll down long enough before. Thanks a million!
Follow-up question: Is there a clever way of avoiding the size limit in the future? It’s not possible to split or automatically create new sheets once the current one is full, right? This would be a brilliant feature! And I think I read somewhere that about 30,000 rows per sheet are the maximum, is that correct? Then I guess I’ll try to keep track and manually split sheets when they are close to that number.
And then one last thing: You don’t happen to know why the .ods export doesn’t work, do you? Opening the .xlsx with Libre Office is a reasonable workaround though, so it’s not a big deal.