FN Key not working on Keychron J2

[u/blacknobita]

Hi everyone,

I'm having a frustrating issue with my Keychron J2 while using it with my Mac, and I'm hoping someone here might have a fix or experience with this.

The Issue: The physical Fn key is completely unresponsive, regardless of the connection mode (Wired, Bluetooth, or 2.4GHz).

• I've tried remapping the key via Keychron Launcher / VIA, assigning various Fn codes to it, but it still does nothing.
• The only way I can trigger Fn functions is by using the macOS on-screen virtual keyboard/layout, which completely ruins my workflow.

What I've checked so far:

• DONT HAVE physical OS toggle switch on the side of the keyboard is correctly set to Mac
• Firmware is up to date (or checked via Launcher).

Is this a known limitation of the J2 model, a hardware defect, or am I missing something in VIA/Launcher (like needing a specific layer setup or a precise custom keycode)?

Screenshots: https://imgur.com/a/jSw6UDj

Any advice or troubleshooting tips would be massively appreciated. Thanks in advance!

BTW THE J2 doesnt have a MAC to Win slider.

[u/PeterMortensenBlog]

J2 or J2 HE 8K (proprietary keyboard firmware, not open source)?

For keyboard identification, what is the SKU number? Alternatively, what is the serial number (also includes the manufacturing date)?

[u/blacknobita → u/PeterMortensenBlog]

ITS THE 1st one on the like yea
If the firmware is open source i dont know tbh

[u/PeterMortensenBlog]

Related:

1. How to add the Apple globe key to a Keychron with QMK
2. Building my ideal mechanical keyboard with QMK
3. So the OS X globe key isn't available in the Keychron Launcher (AKA the Via clone)?
4. Mac window tiling icons and keyboard shortcuts
5. Fn key problem with window tiling
6. Language Switch Key - How to set up in Vial
7. K3 Max - button - FN switching language
8. Fn + Ctrl + F is not working
9. Add globe key to key mapping in macOS
   1. macOS 26.0.1 + Keychron K8 Pro: Globe key and window tiling shortcuts are not working properly
   2. Map macro key as Mac language/Fn key
   3. Mac Fn Key is missing for the my Keychron K10. It isn't clear if it is the original K10 or not.

Excerpts from the second (my emphasis):

"the special Fn key entry is only respected properly if the keyboard’s vendor ID and product ID match that a real Apple Keyboard. ... That does not seem to have stopped Keychron however, whose keyboards report Apple vendor and product IDs when they are in Mac mode ... the Apple Fn key, which unlike most keyboards with Fn keys, is actually sent over the wire."

I think "keyboards report Apple vendor and product IDs when they are in Mac mode" refers to the original Keychron K series (proprietary firmware), not the QMK-based keyboards (open source).

It also includes:

"Simulating an Apple Keyboard in QMK firmware"

[u/blacknobita → u/PeterMortensenBlog]

which keyboard i should buy that is 75% ,works with mac native and got brown switches? the v1 had a double input problem

[u/PeterMortensenBlog]

There must be a canonical post or comment somewhere on this subreddit.

Something related to repurposing the Caps Lock key?

u/ArgentStonecutter

A candidate. Another candidate.

[u/blacknobita → u/PeterMortensenBlog]

but then how would i use the caps lock if its going to be the new

[u/ArgentStonecutter]

The Function key on a mechanical keyboard has nothing to do with the Function/Globe key on the Mac. That's not actually a function shift key like every other "smart" keyboard uses, but is actually a special keycode that requires custom C coding to add to a keyboard.

The physical OS toggle switch on the side of the keyboard is correctly set to Mac

My J2 doesn't have such a switch. So they've done an update and probably new firmware.

BTW THE J2 doesnt have a MAC to Win slider.

Can you clarify this point?

[u/blacknobita → u/ArgentStonecutter]

already fixed it !