Multibus plugins and Logic 10.5

When I load a multibus plugin in Logic 10.5 and restrict the supported layouts with isBusesLayoutSupported Logic still shows some layouts that are not supported.

If I add the following method override to examples/Plugins/MultiOutSynthPluginDemo.h

  bool isBusesLayoutSupported(const BusesLayout& layouts) const override {
const auto& outputs = layouts.outputBuses;
auto isStereo16 = std::all_of(std::begin(outputs), std::end(outputs), [](const AudioChannelSet& bus) {
  return bus == AudioChannelSet::stereo();
}) && outputs.size() == 16;

auto isMono = outputs.size() == 1 && outputs[0] == AudioChannelSet::mono();

auto isStereo = outputs.size() == 1 && outputs[0] == AudioChannelSet::stereo();

return isStereo16 || isMono || isStereo;


Then the following layouts are available:


If I select the two first ones the plugin opens. If I select the third one then I get:


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I had similar issues in < 10.5 preventing the x25 option where I wanted to only allow x16. But can confirm similar behaviour when only wanting to allow 1 bus!

I think something has gone awry with multi-bus in logic 10.5, i keep seesing this 16x stereo and 25x stereo option on plugins that shouldn’t have that config

Logic 10.5 has suddenly broken all the multiout versions of my plugin… I use to have 5x mono, stereo + 3x mono, and now Logic 10.5 is only listing 16x Stereo etc, and fails to instanciate the plugin if I not choosing 1x mono or 1x stereo.

Has anyone reported an issue to Apple ? [edit: I just wrote to their feedback page]

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Do you have a link to that or was it a bug filing report?

I have no link – it’s not a proper bug report: I wrote through