Parity over the biquadratic field $\mathbb Q(i,\sqrt{17})$

Let $K=\mathbb Q(\sqrt{-1},\sqrt{17})$. Biquadratic-field parity conjecture. Every elliptic curve $E/\mathbb Q$ has even Mordell–Weil rank over $K$:

$$\operatorname{rk}E/K\equiv0\pmod2.$$

The proposed statement follows from the parity conjecture because every place of $\mathbb Q$ splits into an even number of places in $K$, giving global root number $+1$. Its unconditional truth is open with the parity conjecture.