We are also getting this problem only in Firefox 58.0.2 that is stopping us upgrade from 5.1.0
You can simulate the issue by modifying the demo example in jqxgrid rowdetails by
increasing grid height to 300
add 6 extra columns { text: ‘Col1’, width: 40 },
You will then notice that rowdetails for ‘First Name’ ‘Nancy’ using the sample data is empty
