helpimnotdrowning

Optionally, change the default "Global Rule" > "Backdrop Type" from "Mica" to "Default" (though not sure what else this affects) 

Ah, nevermind. I had my render distance set at 32. Bringing it down to 16 makes it work perfectly at any resolution.

actually i dont know why I closed this, it should be able to big screenshot at any render distance

I was using Complementary 4.1, my native resolution is 1680x1050 but had Fabrishot set to 8640x6480