Stefán's circular-flow bound conjecture for class 1 odd-regular graphs

Let $t$ be a positive integer and let $G$ be a $(2t+1)$-regular class $1$ graph. Its circular flow number is denoted by $\phi_c(G)$.

Stefán's class 1 circular-flow bound conjecture.

$$\phi_c(G)\le 2+\frac{2}{t}.$$

The source presents this as a conjecture and, in the supplied text, does not state that it has been proved or disproved.