External Monitor Goes Black Randomly After macOS Sequoia 15.5 Update

Hi everyone,

I’m posting here to see if anyone else is facing a similar issue, or has found a real solution.

Since updating my MacBook Pro to macOS Sequoia 15.5, my external monitor (Samsung LC27G55TQBUCEN, via HDMI) randomly turns black for 30–40 seconds and then comes back on. This happens multiple times a day.

Here’s what I’ve tried so far:

• Swapped HDMI cables and ports
• Manually set refresh rate to 60Hz
• Tried Safe Mode (still happens)
• Used the same monitor with my MacBook Air (no issue at all)
• Noticed the Mac still detects two displays when the screen is black
• Contacted Apple Support

Support told me it’s likely a “display issue,” but that doesn’t add up, it worked fine before the macOS update. They also suggested reinstalling macOS, but frankly, I don’t trust that as a solution, especially since they couldn’t give a clear explanation and seemed unsure of the root cause.

I also found an older discussion from Sequoia 15.1.1 and 15.3 with similar symptoms.

This feels like a macOS bug, not a hardware fault. The fact that the display is still detected while blacked out seems to confirm that the connection isn’t being lost, just the video signal.

If anyone else is having this issue, or has figured out a workaround (DisplayPort? older OS? specific adapter?), I’d appreciate hearing about it.