Looks like we are missing some things in order to help. Just to name a few is class, priority attributes in your sample doesn't match your calc, duration calc (assuming start-end dates)...
Ideally we need to see exactly how your data is layed out/containing. It is best to load a sample workbook with either superstore mimicking your data or anonymizing your data set. Anonymize your Tableau Package Data for Sharing The more you can help us seeing the issue the faster we can help.
Fantastic, thank you so much!
This is exactly what I was looking for!
Well, almost - but the simple difference is to turn this into a heatmap and aggregate it per month.
I'll have to check what the ATTR function is doing exactly, without it it seems to be aggregated incorrectly.
Again, thank you SO much!