We're not able to see your work because it is asking for connection to your datasource.
I think you will need to extract your data before packaging:
In general, you may be able to use a lookup filter of the month which will retain the previous
month's data so that you can perform your difference:
I'm sorry about that! Thank you for helping me out. I actually discovered an answer to this very question just this morning, so I will mark this as answered. I will make sure to include an extract version of my data source from here forward.
Have a great day!
No worries. Glad you got the answer.
All the best.