Activity Monitor CPU Usage is grayed out

That usage option ⌘2 under ActivityMonitor>Window>dropdown is a GUI graph of the cores—basically useless really.

⌘1 will open the Activity Monitor Window— here clicking CPU from the tool bar is much more meaningful.

I will add one off anomalies like yours are not easily sorted.

You can try reinstalling the combo update 10.13.6 Download macOS High Sierra 10.13.6 Combo Update

You can try reinstalling the full macOS from Recovery

To trouble shoot further you can:

Try a SafeBoot https://support.apple.com/en-us/HT201262

Takes noticeable longer to get to the login screen as certain system caches, dynamic loader cache etc get cleared and

rebuilt. This test will tell you if third party interference; extensions etc are not loaded in safe boot mode.

Test issue in another user (or guest user) account https://support.apple.com/en-us/HT204443

This will tell you if it a universal issue or isolated to your user/admin account.

Try restarting.

No, it's not how long it's been on. 😎 It's just sometimes things get out of whack and a restart can fix it. It's the easiest thing to try first.

My "CPU History" window option is grayed out if I have the Dock icon showing CPU History. What does your Dock icon look like?

CT is spot on.

If you Control click your Dock icon you can change the window view on the Dock—this supersedes what is available in the larger app window when you open the AM.

betaneptune wrote:

Nope. Still doesn't work from my main account.

As before, I'll try it again the next time I reboot and report back, if the thread doesn't get locked by Apple beforehand! I doubt I'll go further than that.

Good computing betaneptune.

With your same Apple ID you can sign up for a free Developers Account and start a conversation with Apple engineers

Bug Reporter https://bugreport.apple.com/

or

Apple Feedback http://www.apple.com/feedback

leroydouglas wrote:

That usage option ⌘2 under ActivityMonitor>Window is GUI graph—basically useless really.

Nonetheless, it shouldn't be greyed out.

betaneptune wrote:

Why is it useless? On my old mac I could make the CPU window float and keep an eye on it. If there were to be a sustained upsurge I would take note and open the full window to see what's up.

NTL, it is not worth that much troubleshooting.

OTOH, I just tried running AM from 2 other accounts. Not broken there! These accounts are very close to pure vanilla.

I was hoping by this point you had followed through and resolved the anomaly.

The operative word may be "On my old mac" —maybe it is just an old habit who's time is past— YMMV.

NTL do what suits your needs, I proposed a way forward in the most constructive way I know—Maybe with the added information that "2 other accounts. Not broken there"— I would propose jumping straight to a Safeboot and log in—this would be informative. You can get a closer look at your System and third party interference using http://etrecheck.com

I could not agree more: "not worth that much troubleshooting."

Useless of course just my opinion— Never once in all the years could I afford to take up valuable screen real estate with a "floating window," running some 18 apps at all times, maybe 8 in full screen in a development environment. Typically even the AM is open in the background as one of those 18—but I demand a lot out of this 2012 15."

OTOH your demands could very well be different. I will submit too you, If you have a "a sustained upsurge" in CPU your fans are going to ramp up—this is a pretty good indicator minus the GUI.