This is because of the Measure Names pill on the columns shelf. Both axes of your chart are accounting for that, including the bottom, so Tableau doesn't really know how to draw the line because, ultimately, there are two other measures that it expects to be there.
Why not just create an entirely separate sheet for the line chart?
Thanks for chipping in Ken.
I'm trying to replicate a chart from a very large, complex, Excel report as part of converting the whole thing into Tableau (a ball ache in itself) and that's how the original chart was done.
Is there any way I could achieve this? I see that it I can get the line chart to show by using a stacked bar chart option but as soon as I change to separate bars it goes AWOL again.
I heard somewhere that this may be possible by getting the line chart data from a different data source - would that be the only way? All numbers are related though so ideally I'd prefer if they all came from the same source.
BTW Ken Flerlage, I managed to get it working by taking the line chart data from a different excel file (bit of a faff to be honest) and now need to omit the % for Week 1 only for the line chart but keep the bar chart values for week 1.
How do I achieve this?