Hello guys :),
I have a dual axis chart (3 bars - each for price value of different category - and 1 line - showing sum of categories). To make the bars stand next to each other I have created X-axis index, it works fine, but the issue comes when switching parameter of Calendar/Fiscal year . Calendar year is OK - X-Axis 1 = January, 2=February, .... BUT - Fiscal year starts on May, so when I change parameter to Fiscal year, column with data for May has "1" on X-Axis - logically - it is first month for this case. Is it possible - anyhow - to change the description of the X-axis to the month names so it works with Calendar/Fiscal year?
Thanks in advance for any help! :)

index() will always start at 1 here.
In the attached I changed your x-axis calc just to use the month number of the date rather than index.
Is this what you are looking to do?