If you face these kinds of export issues like no data/any other related to export kindly follow the below steps
In case if you are seeing this issue at dashboard level follow below steps
a. first thing is check the export at individual report level if it is working fine
b. then add that specific report in a fresh dashboard then test if it works or not.
c. If the export is not happening at individual report level also then check all the filters labels/data and dragged column names, given alias names if any special characters are present.
In case any special characters are present then rename those filter labels and column names then test the export if it works.