It shouldn't be this easy, but then you did have a non-tubeless ready tyres, my experience is only on tubeless tyres and it should always have a tight to near impossible fit (pray it's not the latter).
Sound like you answer your own question TBH; replace valve.
Yeah, my former experience of Schwalbe's (Pro One TR, Marathon non-TR) has always been painful, as you suggest, so it was a pleasant surprise when it went on without too much of a fight. Just annoying the issue seems to be the valve. Hey ho!
It shouldn't be this easy, but then you did have a non-tubeless ready tyres, my experience is only on tubeless tyres and it should always have a tight to near impossible fit (pray it's not the latter).
Sound like you answer your own question TBH; replace valve.