Audio Unit can't make HTTP request with WebInputStream... but VST3 for some reason can?

The code is pretty simple. In my VST3 and standalone builds, everything works fine. In my Audio Unit build, this always returns -1, and the server never receives a request. (HTTP vs. HTTPS doesn’t matter. I’ve tried both.)

auto url = URL(urlString);
auto webInputStream = new WebInputStream(url, false);

if (webInputStream->isError()) {
    return -1;

Could depend on the host’s permissions. Logic, for example, may be sandboxed. Try VST3 vs. Audio Unit it Studio One. That’s one I know of offhand that supports both. Then you can tell if it’s a problem with the plugin type or the host.

I have this problem on both Logic and the JUCE example plugin host, so I doubt it’s a host thing.

(I also used the example plugin host for comparison w/VST3)