Help with matrix. Show detail and don't summarize

[Anonymous]

I'm working on a report using a live connection to an SSAS model.  I would like to create a table/matrix which shows the transaction month as a column header and then the dates of each transaction as the values.  A matrix gives me the format I would like, but I'm not sure how to have it list each transaction date instead of doing an aggregate.  The image below is what I currently have, but it's only showing the earliest date.

[Anonymous]

@vicky_   Thanks for the help.  However, I would like the dates to be listed directly underneath the month vertically, not horizontally.  Not sure if this is possible, since different months could have a different number of dates.  This is how it shows in Power BI using your suggestion:

Here is how I would like the data to look:

[vicky_ · Accepted solution]

Ah my bad - 
if you just want to SHOW the values, and not have anything else, then you can try creating a measure to return the values as a string (formatted so that it's one date per line). 
Here's a sample measure:

Dates as List = IF(HASONEVALUE('Table'[M / Y]), CONCATENATEX('Table', 'Table'[Dates], UNICHAR(10)))

[vicky_]

You need to set up your matrix like so by putting both the month and the date in the column field:

Note - if you've got a date table (and haven't disabled the auto-date heirarchy), there you can just pop the heirarchy in the columns area.

Either way, you can then simply drill down with the fork icon to show the month and day in the headers