@schanco Yes, please let us know how your Mac connects to the Mix Rack - is it a direct connection, or is there an unmanaged switch, or is it a fully managed network with VLANs etc. like a corporate network?
The MIDI messaging uses one specific TCP/IP port, and Director uses a range of TCP ports as well as UDP. If director works, it is less likely that there is a network problem, but it is theoretically possible for one to work while the other is blocked by a managed switch, router, or firewall.
Director (and, I think MIDI Control) should be able to detect that your Mix Rack exists, and be able to connect to it by name without having to enter an IP address. If not, then the A&H discovery broadcast messages are getting blocked and it is more likely that there is a network issue of some kind.
Also, in Director (or a Surface) check Mix Rack → Control → MIDI → Send/Receive MIDI and make sure that Send and/or Receive are enabled. It for sure will not work if MIDI is disabled.
Check that the MIDI channel range is set to the same on the Mix Rack as it is in MIDI control. If they are different, I think MIDI Control will be able to connect, but the messages will be on different MIDI channels and may or may not come through.
If your dLive is configured with users then I think MIDI Control will also need to log in as a user.
Check whether the send/receive “lights” in the MIDI Control window ever blink. They should show some activity for channel mute/unmute, fader, etc. and when QLab sends to the MIDI port. This could help isolate whether MIDI is making it to/from MIDI control but not to/from QLab.
If I remember correctly, MacOS Audio Midi Setup has a place where you can specify what MIDI channels a device uses, and block unwanted channels. Make sure the channels are enabled there.