"Sync brightness from Built-in and Apple displays" stops working after sleep

Before opening the issue, have you...?

• [X] Searched for existing issues
• [X] Looked through the wiki
• [X] Updated MonitorControl to the latest version (if applicable)

Describe the bug

Syncing brightness from my MacBook Pro 2019 to my Dell display with hardware DDC works fine... until my Mac sleeps. After a sleep cycle, the brightness changes caused by the Ambient light sensor are no longer synced to the external display.

I have verified MonitorControl is still running in Activity Monitor, and brightness changes made by the keyboard shortcuts in MonitorControl are applied successfully to the external display.

If I quick and relaunch MonitorControl, then syncing will resume until the next sleep cycle.

Steps to reproduce

1. Launch MonitorControl with Sync brightness changes enabled.
2. Put the Mac to sleep
3. Cover the light sensor on the Macbook or change the built-in display brightness in System Preferences

Expected behavior

Brightness on both on the displays should adjust. Instead, only the built-in display brightness changes while the external display brightness remains constant.

Anything else?

Environment Information (please complete the following information)

- macOS version: 12.1
- Mac model: MacBook Pro (16-inch, 2019)
- MonitorControl version: 4.0.2
- Monitor(s): DELL U2713HM
- Apple Silicon/M1 (yes or no): no

Do you have this issue only with ambient light sensor? If you change the brightness using the built-in (macOS native) brightness slider, what happens?

Hi, yes as mentioned in step 3 syncing to the external display also stops working when I change the built-in display brightness in System Preferences. The built-in display brightness changes, but the external display doesn't change. I can still use the brightness keys to adjust the external display, but syncing breaks.

All right. We'll look into this, thanks for the report!

To clarify this issue. I've noticed that it's not necessary for the Macbook to fully go to sleep in order for syncing to break.

If I have an application running that prevents sleep (or when Music.app is playing) the displays will turn off after the period of inactivity specified in System Preferences.

When the displays wake up again, brightness syncing will be broken until I quit and restart MonitorControl.

Hi, I just want to add, that I have the same issue under this conditions:

- macOS version: 12.1
- Mac model: iMac (27-inch, 2020)
- MonitorControl version: 4.0.2
- Monitor(s): DELL P2720DC
- Apple Silicon/M1 (yes or no): no

I noticed additionaly that after sleep the brightness sliders in den menu didn't react, if brightness is changed automatically by the built-in sensor. They react only if brightness is changed by keys or by the sliders itself.

- macOS version: 12.3
- Mac model: Macbook Pro (2019)
- MonitorControl version: 4.0.2
- Monitor(s): HP 24es
- Apple Silicon/M1 (yes or no): no

Not sure if it's the same issue, but I noticed that some of the folks above are getting different behaviors than mine, but essentially they all experience some sort of sync issue.

To clarify, there are 4 types of controls I tried:

1. The slider on the touch bar (macbook pro native)
2. The brightness buttons (not a slider) on the same touch bar, when the menu is expanded
3. The brightness buttons on my PC layout keyboard ('F1' & 'F2') (which should be sending the same signals as 2)
4. The brightness slider from MonitorControl in the menu bar (I have it setup as control all so it's probably working regardless of the sync option)

My sync setting is checked, and after sleep I noticed that 1 stops working while 2 and 3, 4 still works.

2 will send proper keyboard commands which are intercepted by MonitorControl so 2,3,4 is the same. So the issue affects only reading 1. upon sleep. We'll have to look into that.

- macOS version: 12.3
- Mac model: Macbook Pro (2019)
- MonitorControl version: 4.0.2
- Monitor(s): T270LG
- Apple Silicon/M1 (yes or no): no

我也遇到了这个问题。希望能修复，感谢。

• macOS version: 12.3
• Mac model: Macbook Pro (2020)
• MonitorControl version: 4.0.2 build 6965
• Monitor(s): S24H85x
• Apple Silicon/M1 (yes or no): no

I'm also experiencing this issue.

- macOS version: 12.5
- Mac model: MacBook Pro (13-inch, 2018)
- MonitorControl version: 4.1.0 build 7034
- Monitor(s): HP 5DQ99AA
- Apple Silicon/M1 (yes or no): no

I'm experiencing the same issue on the latest available version. Type 2, 3, and 4 work, but Type 1 nor the sliders in the control center and System Preferences won't work.

By the way, thanks for this fantastic software!

I'm also experiencing this issue.

- macOS version: 12.5.1
- Mac model: MacBook Pro (16-inch, 2019)
- MonitorControl version: 4.1.0 build 7034
- Monitor(s): Dell s2721dgfa
- Apple Silicon/M1 (yes or no): no

Now on Ventura and still experiencing this.

- macOS version: 13.3
- Mac model: MacBook Pro (16-inch, 2019)
- MonitorControl version: 4.1.0 build 7034
- Monitor(s): Dell U3223QE
- Apple Silicon/M1 (yes or no): no

I'm also experiencing this issue.

- macOS version: 12.6.8 (21G725)
- Mac model: MacBook Pro (15-inch, 2017)
- MonitorControl version: 4.1.0 build 7034
- Monitor(s): HP E24d G4 Display * 2
- Apple Silicon/M1 (yes or no): no

I'm also having this issue.

- macOS version: 13.6.1
- Mac model: iMac (27-inch, 2017)
- MonitorControl version: 4.2.0
- Monitor(s): Dell P2222H
- Apple Silicon/M1 (yes or no): no