Library Histogram Not Always Available

From your system information

Displays: 1) 3360x2100

Now , I do not remember a MAC Book Pro, including Retina, with that resolution, So is that an external monitor? And as only one display value Is listed, the laptop cover is closed? Or does your rig actually run at 3369x2109?

Got off main issue/subject, returning

Lightroom does not perform well at higher resolutions

2K, Ok

3K, slow, especially in Develop module once you get into brushes (adjustment, graduation, radial)

4K, very slow, can be even in Library if Standard previews too high.

5K, extremely slow, Develop module painfull.

Now, as one member stated, Adobe needs to fix this, we buy nicer monitors for a reason.

But moving on to the here and now,

If this is the laptops screen, you are probably stuck with Apples solution of scaling and cannot actualy truely reduce the resolution, you can however decrease the standard previews to 2K or less, to help in Library, you can decrease your screen size (that is do not run full screen ) to help in develop module, and/or (one I keep forgetting) in Finder, navigate to the Lightroom app, right click and select get info, and check the box to open in low resolution.

oh, some clarity in: Using a Retina display - Apple Support  at least on my previous sentence about low resolution.

If it is a external monitor, decrease the resolution at the monitor, and adjust MAC OS settings as required.

Remember one thing. In Library module the previews created and kept in the lrdata directory (folder) are used. In a Develop mode previews are created on the fly and are stored in the Camera RAW CACHE. Library and Develop use different previews. And in Develop, each time you make an adjustment, a new preview is created. And the more pixels to fill on the display, the more pixels to render when creating Develop previews,

yes, I know, Adobe Adobe Adobe, but to get things working.

All that said, this might have nothing to do with your histogram display issue, but if your issue is that the histogram appearing takes too much time....

Second issue, just a P.S. I notice that your Adobe Creative Cloud Desktop wants your attention. (red dot)

A couple of things

1. Lets clear up some information, in case it helps. To provide a provable answer to what is your system information, in LR click on Help, click on System Information, Click on Copy. Paste results from top to just after presets in a reply, Interested in LR version, CC Licenses status (basicaly that it is not Unknown) OS version, Display resolution, GPU make and GPU driver version, if or if not Direct is running, and a glimps at any odd plugins that are enabled (not likely this issue)

Show us a screen shot of the whole LR window with one of the images selected that does not show a histogram.

Is your Mac plugged in to AC power or on battery when this happens. Are these JPG or RAW images?