Logitech MX Ergo extra button ("Button 12") no longer detected in 6.539

Bugs or Unexpected Behavior
1

Hi,

The extra/precision button on my Logitech MX Ergo trackball (the one BTT labels as "Button 12") stopped being detected after updating BTT. It works perfectly on an older build but is completely unrecognized on the newest one.

Environment

  • Mac: Apple M4 Max, macOS 26.5.1 (build 25F80)

  • Device: Logitech MX Ergo Multi-Device Trackball (configured via "Logitech Mouse Configuration" in BTT's Normal Mouse section)

  • "Make All Buttons Available For Remapping in BTT": enabled

  • Logitech Options+ / G HUB: NOT installed (no Logitech software present at all)

Works vs. broken

  • BTT 6.500 (build 2026050804) → pressing the extra button is detected as "Button 12" and my mapping (send Return) fires correctly.

  • BTT 6.539 (build 2026060402) → pressing the same physical button does nothing; BTT does not register any button event at all (no number appears when I try to record it).

  • Standard buttons (left/right/middle) still work in 6.539 — only the Logitech extra button is affected.

Steps to reproduce (on 6.539)

  1. Set up the MX Ergo via "Logitech Mouse Configuration", enable "Make all buttons available to BTT".

  2. Try to add/record a Normal Mouse trigger and press the precision/extra button.

  3. Nothing is detected (on 6.500 this shows "Button 12").

Note
This looks like a regression in the Logitech (HID++) integration's reading of the MX Ergo extra button between 6.500 and 6.539. The stored trigger (same UUID) is intact; the problem is that the physical button no longer produces any event BTT can see on 6.539.

2

That still seems to work fine with my MX Ergo. Could you try collecting the device logs?

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3

This is a report to let you know the issue is resolved; sorry for the trouble! It turned out that the reason Button 12 stopped working was because the target device in the Logitech Mouse Configuration was unselected (left as "choose"). Once I re-selected the MX Ergo, the button inputs were captured correctly and it worked perfectly. This was my own configuration error, not an actual bug. Sorry for the inconvenience!

(Note: It seems the device selection was reset to "choose" at some point, perhaps during an update. If anyone else experiences the same issue, it might be worth checking your Logitech settings to see if your device is still selected.)

4

Could you check whether it continues to work with 6.542? (I added some more fallback exceptions in the hope they would fix the issue)