Were you able to resolve the issue. I am facing the same issue. I got 4 expressions 2 for Bars displaying Actual and Target and 2 for lines displaying FY Actual and FY Target. Upon publishing FY Actual line disappears, data source file is in place and so is the variable. I tried replacing the variable with its expression and publishing it, yet the line disappears. I tried deleting the object and creating a new one, but in vain.
I tried using a cross table, the issue still persists. I deleted all the tabs and created a new tab with the charts but to no avail.