The compiler never targets loops other than innermost ones, so it vectorized the inner loop while did not vectorize the outer loop. However outer loop vectorization could be more profitable because of better Memory Access Pattern, higher Trip Counts or better Dependencies profile.
To enforce outer loop vectorization:

Target	Directive
Outer loop	!$OMP SIMD
Inner loop	!$OMP NOVECTOR

Given issue is only about opportunity to vectorize outer loop, to prove profitability you need perform deeper dive analysis (MAP, Trip Counts, Dependencies)

Example

!$OMP SIMD
DO I=1,N
    !$OMP NOVECTOR
    DO J=1,N
...

!$OMP SIMD
DO I=1,N
    !$OMP NOVECTOR
    DO J=1,N
        SUM = SUM + A(i)*A(j)
    ENDDO
ENDDO