Okay, so with this formula, I believe you are not looking for "Date" which is column A but "ymd_first_service" which is column H.

=SUMIFS(tbData[[P2 ]],tbData[gfap],IF($I$2="All","*",$I$2),tbData[Location],$B$2,tbData[Unique patients],1,tbData[ymd_first_service],">="&E$5,tbData[ymd_first_service],"<"&EDATE(E$5,1))