How would I write a calculation to show fields if NOT All filter values are selected?

I'm trying to create a calculation that lists out fields as a text string (with commas) only if NOT All fields are selected in the filter otherwise display the text "All" (or hide it from the dashboard).

The issue I'm running into is the "All" text is being duplicated by the number of values (because of the dimension on the detail mark).

I attached a sample .tbwx dashboard to show what is happening but I tried something along the lines of:

IF TOTAL(COUNTD(Segment)) = SUM({FIXED :COUNTD(Segment)}) THEN "All"

ELSE

(IF LAST()!=0 THEN MIN(Segment)+","

ELSE MIN(Segment)

END)

END

For context, I'm trying to create a sort of a Appendix dashboard that lists out all filter selection values but it isn't necessary to see if the selection is All.

Any advice would be great.