Totally missed that, thanks! I don't know the library very well, but as far as I can tell they don't support .xyxy style sizzling with the SIMD Vec4 type.

They're using the same "proxy object" method I was doing for their sizzling which I'm pretty sure won't work with SIMD types but would love to be proven wrong!

I haven't deep dived into the library as I'm no longer doing this kind of code.