It seems your program is returning a pivot value when there is none. You may want to check and see if your program works for large lists with similar numbers that contains an even number of elements.

ints = [1,1,1,1,1,1]
# Has no index where the pivot has the left and right sums equal to one another

ints = [1,1,1,1,1,1,1]
#       ^---^   ^---^
#         3   =   3