Hi
Thanks for coming back. It's good to know whether you're working with a measure or a column - I assumed a column. You won't get the Don't summarize option with a measure as measures are always aggregations and can't work as a grouping like you want in this case.
The challenge you'll have here is that the measure is going to perform as an aggregation of the values for the current row context - without a suitable accompanying column/field in the visual to group by, you're likely to always get a scalar (single) value because there are no rows in the resulting dataset.
The fact that you're using KEEPFILTERS implies that you're wanting this measure to be dynamic based on filter context?
What you want is quite an advanced scenario (at least for me!) and I think it needs a wider audience for input. I would suggest cross-posting this question in the previously-linked DAX forum with as much info as possible and I'm optimistic they can help you much faster than if the question remains open here.
Good luck!
Daniel