Drilldown not working on published report

OK....   I have managed to find a solution....   here goes!

It appears to be related to the type of data I'm using and the order in which I put my heirachies together...

In my original report, my first heirachy was a date.  PBI automatically turned the date into it's own heirachy of year/month/day.  I didn't want 3 layers to drilldown for date as I only had 1 day in each month represented in my dataset (invoice date)... so...  I turned off the auto-heirachy for this field.  This subsequently removed the option to enable drill-down in PBI, despite the fact there were other levels beneath InvoiceDate.  I'm guessing this is a bug in the PBI behaviour??

Fix...  

a) add in all levels of heirachy with my date at the bottom (ie, not in the order I wanted it for drill down)

b) remove the auto-heirachy added to the InvoiceDate field

c) check the 'enable drill down' arrow was present when viewing my top level of data

d) change the field order for the axis data to put my InvoiceDate field back at the top

Doing it in this order prevented the 'Enable Drill Down' from disappearing unexpectedly.

Publishing the report after all this allows it to work correctly in PBI Web

Hope this helps someone else!

Cheers

Mike