Dub arch type doesn't have any effect

[Reavershark]

Setting the dub arch type in a workspace, either through the "Switch Arch Type" command or the "d.dubArchType" setting, has no effect.

In an example project with:

dub.sdl:

name "x86test"
targetType "staticLibrary"

source/app.d:

static assert(is(size_t == uint));

extern(C)
int main() => 0;

.vscode/settings.json:

{
    "d.dubArchType": "x86"
}

Running dub build fails with Error: static assert: is(ulong == uint) is false.
Running dub build -ax86 succeeds.

Code-d will always show the same error, even when x86 is selected:

(Switching to dmd doesn't help)