External monitor fail to wake from sleep

[gthyena]

Hello everyone. I have a small problem with my Macbook Pro Retina 13" 2015 with El Capitan GM candidate when it's connected with my Acer 23" monitor.

Whenever my system or display goes to sleep and my Acer monitor goes to standby mode (amber light), the Acer monitor will fail to wake up when my MBP does.

I've rested my PRAM and SMC several times with no luck.

I connected the Acer monitor with HDMI>Thunderbolt (tried both ports) and HDMI port along. All produce the same problem.

When the Acer monitor goes standby (Amber light), the system does not recognize the Acer monitor and I can feel lagging when I move my cursor around. In Activity Monitor, I start seeing processes displaypolicyd and mdworker using some CPU resources.

When the Acer monitor is completely turned off, the system will recognize it and extend the display as I set it.

The only way for me to solve the problem is to turn the Acer monitor completely off and on again.

When the Acer monitor is on, there's no problem when I'm using it.

I've had this monitor for a while, and before I used a MBA 13" 2011 with the same connection and adaptor without any problems.

To me it seems like a software/firmware issue.

Anyone here experiences the same problem?

 

[snaky69]

You're using a beta OS. You're supposed to expect bugs. I'd wait until El Capitan is ready for primetime. Until then, file a bug report.

 

[gthyena]

You're using a beta OS. You're supposed to expect bugs. I'd wait until El Capitan is ready for primetime. Until then, file a bug report.

This problem also occurs in Yosemite 10.10.5.

Also, after a long sleep connected with external display, the system will fail to wake from sleep.

Not sure what I should do at this point. It's a pretty annoying issue.