Chord plugins send MIDI that your DAW may never receive

A plugin that generates chords and melodies has to hand those notes to something that actually makes sound, and that handover is where most songwriting tools quietly fall apart, because the plugin format doing the generating, the DAW doing the hosting and the routing menu you have never opened all have to agree before a single note reaches your piano patch, and on a Mac running Logic Pro that agreement is not available at all. Ableton is blunt about the reason. The Audio Unit standard does not support a direct MIDI out.

That single line explains an enormous amount of frustration. Logic Pro loads Audio Units and nothing else, so a chord generator running there has no supported path to push notes at a separate instrument track. You will hear it play, and you will not be able to send it anywhere.

The workaround Apple never built has been circulating for years. You switch on the IAC Driver, duplicate the track, swap the original instrument for External Instrument, point its MIDI destination at an IAC bus, strip the generating plugin off the copy, and record the result. Nobody enjoys this.

Audio Units were never built to send MIDI out​

On Windows the problem largely disappears, because VST3 carries MIDI output as part of the specification and hosts on that side expose it. Mac users get the same escape route whenever a developer ships both formats. Load the VST3 rather than the AU, and the routing menus wake up.

That choice is not always there. Logic Pro will not load a VST3 under any circumstances, so on Mac the format that solves the problem is the one format Logic cannot see. Ableton Live, Cubase, Reaper and Studio One all can.

Drag-and-drop sidesteps the whole mess, and the songwriting canvas Song Cage just parked in the DAW leans on exactly that, turning chord and melody parts into editable clips you drop onto a track. The notes land as data you can edit, not as a live stream you have to chase.

Ableton needs the second track set to monitor in​

Live's own instructions run to four steps, and one setting people forget. Put the generating plugin on a MIDI track, make a second MIDI track, then set its MIDI From chooser to the first track and its input channel chooser to the plugin itself. The forgotten step is the monitor button.

Set that receiving track's monitor to In. Skip it, and you get the receiving track sitting there in total silence, which sends most people back to the manual convinced the plugin is broken. Live is simply not listening yet.

Channel assignments matter once a plugin outputs more than one part. A tool that puts chords on MIDI channel one and melody on channel two needs two receiving tracks filtering separately, or one instrument that handles both. Get this wrong, and your bass patch plays the topline.

FL Studio matches port numbers, or nothing plays​

FL Studio handles it differently and more bluntly. You open the wrapper settings on the generating plugin, set an output port number, then open the receiving instrument and set its input port to that same number. Both values must match, and the number must not be in use anywhere else.
The number itself means nothing. Uniqueness is the entire rule, which makes port conflicts the standard failure once a project grows past a handful of routed plugins. Keep a note of what you have used.

Pro Tools sits outside all of this, because AAX builds tend to arrive later than AU and VST3, when they arrive at all. The format list on a product page decides more about your daily workflow than the feature list does. Most people read it last.