Connectivity conjecture for minors of k-polymatroids

Let $M$ be a connected $k$-polymatroid and let $N$ be a connected minor of $M$. A connected minor-preserving deletion or contraction is a deletion or contraction that remains connected and retains $N$ as a minor. Connectivity conjecture. When $N \neq M$, there is an element $e$ of $E(M)-E(N)$ such that $M\backslash e$ or $M/e$ is connected and has $N$ as a minor.

The paper proves this assertion for $2$-polymatroids and suggests that the same result should hold for all $k>2$; its status is therefore unresolved in the supplied source.