Based on my test using Power bi desktop version : 2.76.5678.782 64-bit (December 2019). I canot reproduce your issue here. And I'm using Excel 2016.
Could you please update your Power bi desktop and check agian? Or you can share your sample data to me if you don't have any Confidential Information. Please upload your files to One Drive and share the link here.
Community Support Team _ Frank If this post helps, then please consider Accept it as the solution to help the others find it more quickly.