Hey andy,
I'm still looking into hiding the months that have 0 cases created in them but I can give you some info on how to show only the last 6 months. You'll need to add some actions to your screen which is generating the report and then use that data as the filter in the Generate Report action.
In a nutshell I assigned the current date/time to an Action Result, used that in a Date Function action to grab the first day of the current month, used that in a Date Add action to add -6 months (subtract 6 months) from the first day of the current month, then used that as my filter in the Generate Report action. Screenshot of my actions below.
- Ashur