Why does water lank level differ between levels and brief view

I have a new ekrano gx with venus os version 3.55 installed.

The water and fuel tanks have wema s3 sender fitted. There is a 1% difference between the levels reported on Levels view versus the brief view. Why is is this and can i solve it?

I know I am arguing about only 1% on systems that are generally an estimation anyway, but it seems to me that the venus os software should be consistent in how it handles data.

Screenshots below, and thoughts / help much appreicated.

Alex