Title: Teensy 4.1 not recognized on macOS Tahoe 26.5.2 - nothing in System Report

[wheeel]

Hi everyone,

I'm having trouble getting my Teensy 4.1 recognized on macOS Tahoe 26.5.2. Here's what I'm experiencing and what I've tried:

Setup:

• Teensy 4.1 with Audio Shield Rev D stacked on top
• macOS Tahoe 26.5.2
• Arduino IDE 2.x with Teensy board support installed via Boards Manager

The problem:
The Teensy does not show up anywhere in System Report → USB. No HID device, no serial device, nothing.

What I've tried:

• Multiple USB cables (known data-capable cables)
• Every USB port on my Mac
• Removed the Audio Shield and tested bare Teensy only
• Performed the 15-second button restore — LED blinked orange and rebooted successfully
• After restore, orange LED blinks normally but still nothing in System Report
• Checked for Teensy ports in Arduino IDE — none appear

What works:

• The LED blinks when powered
• The 15-second restore completed successfully
• The program button causes the LED to blink red

Has anyone gotten Teensy 4.1 working on macOS Tahoe? Is this a known compatibility issue? Any help appreciated.

Thanks!

 

[CollinK]

I have found that MacOS 26, or at least the M1 Macbook Air I have, is very picky about the USB standard. So far as I've seen, macs with M series processors tend to have a whole lot of USB-C ports and not much else. USB-C requires that the CC pins be held to proper states to show the cable and device capabilities. Other machines seem to be willing to fudge the rules a bit and let USB-C connected devices default down to USB2 and work. The MacBook Air certainly does NOT. It requires that the CC pins be properly handled. I have a USB-C hub that connects via USB-C and provides 4 USB-A ports. The Mac does not like this and refuses to allow any data this way. I have to use a more expensive (X in 1) style dongle - the sort that have an ethernet port, HDMI, and other ports on them. Such a device does tend to handle CC properly so then devices connected through it will work even if they're USB-A or USB-B. This might be your problem. Do you have USB-A ports on your Mac?

 

[PaulS]

No problem here. MacOS Tahoe 26.6.2.

Using a no-name USB A-to-C adapter:

Paul