Using three USB microphones for Garageband

I have a MacBook with a USB-C and uses a USB hub with 3 USB ports. I want to record a podcast with 3 USB microphones in Garageband. If I record with each microphone separately, it works. If I use 2 microphones, no matter what brand, it works. But if I use all 3 microphones they don't work together. Does anyone know why this can be? I use the MIDI tool to put all 3 microphones into a connected unit and choose this when starting a new project in Garageband.