Art Conductor doesn't connect to Metagrid/PlugTools

Support & Troubleshooting Logic Pro
1

Hi,
I’m having trouble getting Art Conductor to work in MetaGrid Pro. PlugTools connects to Logic Pro without any issue, but the Art Conductor connection to MetaGrid never comes up — MetaGrid’s status stays on “No Data Received” no matter what I try.

Setup:

  • MetaServer: 6.1.3, Build 4335
  • PlugTools: 5.3, Build 2
  • Art Conductor: Art Conductor 26 (Logic)
  • macOS 26.6.2, Apple Silicon, German keyboard layout
  • Connected via USB, iPad

What works:

  • General MetaGrid Pro controls
  • Logic Pro shortcuts/commands
  • PlugTools shortcuts I’ve set up myself
  • Test Logic Pro Connection in PlugTools → Passed

What doesn’t work:

  • Test Metagrid Connection in PlugTools → never completes. It asks me to perform an action to test the connection, but the test just hangs waiting for that action indefinitely.
  • MetaGrid’s Art Conductor object shows Status: No Data Received permanently.

MetaServer console log (on every launch):

[midi-port] MIDI client created
[midi-port] created source port: Metasystem – MIDI – In
[midi-port] created destination port: Metasystem – MIDI – Out
[midi-port] FAILED MIDIPortConnectSource for port 0 (Metasystem – MIDI – In): OSStatus=-50
[midi-port] FAILED MIDIObjectSetIntegerProperty(uniqueID=0) for midiPortIn0: OSStatus=-50
[midi-port] port 0 initialized (metasystem)
[midi-port] created source port: Metasystem – StudioPro – In
[midi-port] created destination port: Metasystem – StudioPro – Out
[midi-port] FAILED MIDIPortConnectSource for port 2 (Metasystem – StudioPro – In): OSStatus=-50
[midi-port] FAILED MIDIObjectSetIntegerProperty(uniqueID=0) for midiPortIn2: OSStatus=-50
[midi-port] port 2 initialized (studioOne)
[midi-port] created source port: Metasystem – Logic – In
[midi-port] created destination port: Metasystem – Logic – Out
[midi-port] FAILED MIDIPortConnectSource for port 3 (Metasystem – Logic – In): OSStatus=-50
[midi-port] FAILED MIDIObjectSetIntegerProperty(uniqueID=0) for midiPortIn3: OSStatus=-50
[midi-port] port 3 initialized (logic)

All three MIDI ports MetaServer creates fail with the identical OSStatus=-50 error, every single launch — including right after a full Mac restart, so it’s not a session/cache issue. Since it hits every port and not just one, it looks like it sits in MetaServer’s own MIDI setup rather than being specific to PlugTools or Art Conductor.

Is this a known bug, and is there a fix or workaround?