Mac Mini display won't consistently sleep

Last night the display failed to sleep once again, and I think I am seeing a pattern. Firefox was running.

The display had just put itself to sleep as it should, I woke it, minimized Firefox, turned on the TV, turned off the monitor, and played some TV shows with VLC. The display did not sleep, 8 hours later it was still up.

I do not remember the last time the display failed to sleep where Firefox was not running. As I previously stated, I am a student, so i often have to leave browser tabs open overnight while I work on things, much of the classwork being online.

What can I do to fix this? To have to close Firefox each night will be a major hindrance to my workflow.

Seriously, I would pay Apple to fix this. I don't want to have to replace this with a PC I hate Windows. I miss the dependability of my old Apple stuff.

Thank you

Maybe my use of "sleep" is incorrect, this is more in reference to "Turn display off after:" under System Preferences>Energy Saver. The computer is not shutting off the displays when it is supposed to, only sometimes, and it requires a reboot to correct.

Unfortunately none of this has worked. Weeks ago I unchecked everything in Energy Saver, I no longer use Bluetooth at all and keep it completely turned off (since it errors out all the time anyway), yet still the computer randomly is not turning off the displays. I will come home from work and the display has randomly been on all day, and I am waking up in the middle of the night to my TV on because the computer isn't cutting signal to it when it should. A reboot fixes it, maybe for a day, maybe for a week, but not permanently. I am trying to reboot the computer every day now, but that is a major hassle to remember, and I know it shouldn't have to be this way.

Is there anything else I can try before I replace this thing with a Windows machine? Are there any other relevant settings hidden somewhere? Are there any sort of logs that might indicate what is standing in the way of turning displays off?

My 2009 Mini this replaced never gave me trouble like this, even when it was 10 years old, I simply do not have room in my life for devices that are this unreliable, the rest of the problems I can live with but if I can't get this issue in particular sorted this thing is gonna have to go.

Thank you for any additional help you can provide.

Is that function actually relevant to display shut-off or are you just speculating? I'll try it, obviously, but I see no reason to expect any change, unless that feature does far more than its description lets on.

Is there any way to get Apple to step in this? I will pay.

My only alternative is to start shopping for a Windows computer, I would try a another Mini but why should I expect it to not just do the same thing? This computer's repeated failures to shut off the displays when it is configured to is having far too negative effect on my sleep for me to continue using it. I truly hate the Windows GUI but I need something that works reliably, its really a shame how far downhill Apple quality has slid, their stuff all used to be so solid.

Here is the current status of Energy Saver.:

A week or so ago I checked the hard disk sleep option, trying to get my multiple external USB platter drives to not constantly spin, and it has had no effect on the display sleep issue. I only reselected "Prevent computer..." today but it may be a week or more until we would know if it has had any effect.

I have noticed that Mozilla Firefox has been open the last two times the displays have stayed on. I try to keep apps closed, but I'm in school and sometimes need to leave tabs open for a day or two while studying.

There aren't any event logs that would cover this sort of thing?

Thank you very much.

I typically access files on the external drives multiple times per day. I guess i will switch it off, part of what prompted the change was the slight noise from the platters spinning, but its not really that bad.

One downfall to selecting "Prevent computer from sleeping" is that now my illuminated mechanical keyboard emits a dim light even when the lighting is turned "off" requiring me to place a cover over it at night as it partially illuminates the room. I am not exactly sure how "Sleep" works or options on when it it is triggered, but apparently it cuts power to the keyboard shutting it off fully, which can not otherwise happen without physically unplugging it. I have had the display issue occur with the setting selected and not selected, but if you all think there is still troubleshooting value in leaving it selected I will leave it be for now.

Now I have a new one..... the computer randomly displayed a screen saver instead of turning off the display. I have never had a screen saver set on this machine, haven't used one at all in 10+ years. It was a dark gray Apple logo and the computer's name individually bouncing around a black screen very slowly.

What is going on here?

I had to switch back to an older OS because I had too many compatibility issues with Monterrey, several of my most used/must have apps won't work on it at all.

Thanks, i just did that, will know within a few days if it worked.