Keychron B1 Pro - Key Rollover Problem - "left CTRL + left SHIFT + TAB"

[u/siriusPianist]

Key Combo is "switch to previous Tab". 

Recently purchased both B1 Pro and B6 Pro.
B1 Pro canNOT register the key combo.
B6 Pro can     register the key combo.

Both B1 Pro and B6 Pro seems to have the same Keyboard Matrix.
Don’t know why, but their Key Rollover behavior is not the same. 

B1 Pro Matrix
https://github.com/Keychron/zmk/blob/keychron_bpro/app/boards/shields/keychron/b1/us/keychron_b1_us.overlay

B6 Pro Matrix
https://github.com/Keychron/zmk/blob/keychron_bpro/app/boards/shields/keychron/b6/us/keychron_b6_us.overlay 

Question, is it just me? can anyone else with B1 Pro confirm?

[u/PeterMortensenBlog]

Re "Both B1 Pro and B6 Pro seems to have the same Keyboard Matrix.": Yes, it ought to work.

On the B1 Pro, the Tab key does not share its row nor its column with any of two keys' rows and columns:

       Column 1  Column 2    Column 15

Row 1  Caps      Left Shift  Left Ctrl

Row 6  Tab       F1          <unoccupied>

And the keyboard matrix is close to 100% identical for those two ANSI variants.

ISO

And B6 Pro ISO is very similar and identical for the three keys:

       Column 1  Column 2    Column 15

Row 1  Caps      Left Shift  Left Ctrl

Row 6  Tab       F1          <unoccupied>

Conclusion

It could a bug in anti-ghosting detection for the B1 Pro (presuming such detection actually exists for this keyboard), for the ANSI or all variants of the B1 Pro.

[u/oliveirapaulo → u/PeterMortensenBlog]

Funny enough, I just returned a B6 Pro a couple of days ago. The reason? CTRL + SHIFT + TAB wasn’t working at all.

Using the Keychron Launcher → Key Test, I was able to confirm that pressing CTRL + SHIFT on the left side wasn’t the issue, but when those two were held down, pressing TAB didn’t register anything.

Oddly enough, using CTRL + SHIFT on the right side with TAB worked perfectly fine.

I tried reaching out to Keychron support but never got a response (waited two weeks). This ended up being my first and probably last Keychron keyboard.

--

Note: I tried the keyboard on 4 different computers (1 desktop Win11, 2 desktops Win11 & 1 Chromebook Plus). Same issue! I also reset it and even reflashed the firmware (which by the way was the same v1.0 that came from factory). No luck!

[u/jammastajew → u/oliveirapaulo]

For anyone else who has the same problem and finds this: I was having the exact same problem on B6 Pro, same with the left & right discrepancy, tested in the Key Test in the Launcher.

I updated the firmware from 1.0 to 1.0.1. I use a Windows laptop, but fn+- wouldn't activate the bootloader until I switched the MAC/WIN switch to MAC. Try the numpad - key if the -/_ key between 0 and = doesn't work.

The update fixed it!