I used to be able to cut and paste Excel line charts into Illustrator and to apply stroke formatting to the lines there. These days – online charts with lots of data points this results in an outlined stroke (i.e. a fill with no stroke). This also appears when exporting as a PDF and opening in illustrator. This applies to charts with no effects applied.
Sometimes I can get around this by opening in open office and exporting as a PDF, or saving as an
.xls file and opening on an older version of Excel – but this regularly fails (either it won't open or won't draw the chart).
Does anyone have a clue how to get back to single lines rather than outlines?