Excel is not recognizing this LAMBDA/LET combo formula as a formula (receiving the 'there's a problem with this formula' error). I thought it might have been something to do with the variable names I was using, but I've changed them and that doesn't seem to have fixed it. I think another possibility is that I have a typo somewhere but I've poured over it and I can't find it.
The error moves the cursor to 'f_R,data!$T:$T,' when the error is thrown, which I think implies the error occurs here, but when I remove this portion from the entire formula, the error is still thrown and just points to the next name/value pair in the LET function.
=LAMBDA(d,f_1,v_1,[f_2],[v_2],[f_3],[v_3],[f_4],[v_4],
LET(
dR,INDIRECT("data!"&REPLACE(ADDRESS(1,MATCH(d,data!$4:$4,0),4),FIND(1,ADDRESS(1,MATCH(d,data!$4:$4,0),4)),1,"")&":"&REPLACE(ADDRESS(1,MATCH(d,data!$4:$4,0),4),FIND(1,ADDRESS(1,MATCH(d,data!$4:$4,0),4)),1,"")),
f_R,data!$T:$T,
c1,INDIRECT("data!"&LEFT(ADDRESS(1,MATCH(f_1,detail[#Headers],0)),(LEN(ADDRESS(1,MATCH(f_1,detail[#Headers],0)))-2))&":"&LEFT(ADDRESS(1,MATCH(f_1,detail[#Headers],0)),(LEN(ADDRESS(1,MATCH(f_1,detail[#Headers],0)))-2))),
c2,INDIRECT("data!"&LEFT(ADDRESS(1,MATCH(f_2,detail[#Headers],0)),(LEN(ADDRESS(1,MATCH(f_2,detail[#Headers],0)))-2))&":"&LEFT(ADDRESS(1,MATCH(f_2,detail[#Headers],0)),(LEN(ADDRESS(1,MATCH(f_2,detail[#Headers],0)))-2))),
c3,INDIRECT("data!"&LEFT(ADDRESS(1,MATCH(f_3,detail[#Headers],0)),(LEN(ADDRESS(1,MATCH(f_3,detail[#Headers],0)))-2))&":"&LEFT(ADDRESS(1,MATCH(f_3,detail[#Headers],0)),(LEN(ADDRESS(1,MATCH(f_3,detail[#Headers],0)))-2))),
c4,INDIRECT("data!"&LEFT(ADDRESS(1,MATCH(f_4,detail[#Headers],0)),(LEN(ADDRESS(1,MATCH(f_4,detail[#Headers],0)))-2))&":"&LEFT(ADDRESS(1,MATCH(f_4,detail[#Headers],0)),(LEN(ADDRESS(1,MATCH(f_4,detail[#Headers],0)))-2))),
IFS(
ISOMITTED(2f),SUMIFS(dR,dR,1,f_R,"F",c1,v_1),
ISOMITTED(3f),SUMIFS(dR,dR,1,f_R,"F",c1,v_1,c2,v_2),
ISOMITTED(4f),SUMIFS(dR,dR,1,f_R,"F",c1,v_1,c2,v_2,c3,v_3),
TRUE,SUMIFS(dR,dR,1,f_R,"F",c1,v_1,c2,v_2,c3,v_3,c4,v_4))))
(DATE(2022,7,31),"Home Department Description","*","Home Department Description","*","Home Department Description","*")