When I click the iCloud icon in Apple System Preferences it is not responsive

Thank you for your reply.

To answer your questions:

I deleted photos one by one, clicking photo and then delete: first on Mac Photos, and then at iCloud photos, and in both cases emptied, deleted, the 'recently deleted album' too.

(Did I perhaps confuse things by doing to much of 'the work' of deleting manually?)

The number of photos listed is decreased in both places by hundreds, matching that they are deleted.

That part of the challenge is okay -- but the actual issue is that I can't get into Apple > System Preferences > iCloud.

When I click this icon the spinning wheel happens within the panel and even on the close, so can only close it by force quitting System Preferences (and that feels as if something might be seriously wrong).

My hunch is that I should leave it all alone for 40 days and then check in to see it it has worked itself out.

I sounds like you might agree.

I read the article you suggested. My Mac Photos 1.0.1 (215.65.0) doesn't have the information

that is presented in this article only: 797 Photos 17 video. If I understand the article it says that

this information about MacPhotos and iCloud Photos and how they are interacting will be at

the bottom on the screen, if iCloud Photos is on -- and I get a note at MacPhotos to sign in to

iCloud Photos (which I presume I have done when I go there and sign in).

At iCloud it says: 846 Photos & Videos Updated 1:17pm today

This shows the right approximate number for the several hundred images I deleted.

Curious is that the last updating was in Nov 2017 -- but that might be as I was at about

1300 photos and perhaps reached the about 1600 images I read you can store for free.

The article says that the synch happens only if iCloud Photos is on. I did choose for it

to operate in the Apple>sys pref> iCloud options -- but as I have been saying, I can't

get in there to check it because when I try I get the spinning wheel. Once I reached

the limit of the images one can put on iCloud for free, might it have automatically 'shut off'?

-- and for now I can't check to see if that is so at Apple Sys Pref > iCloud (as explained).

Is my reasoning correct that doing all that I have: deleting manually from both MacPhoto

first and then iCloudPhoto; perhaps the iCloud Photos filling with 1300 images for the free

space allotted, and then deleting the deleted items at first Mac Photo and then iCloud Photo

has basically 'mixed up the messages' being sent and received by the Mac system?

Thank you for the suggestion, very much. I am going to wait for the 30-40 days

after all I have put the system through (and myself) and then if it is still showing

a spinning wheel when I go to Apple Sys Pref > iCloud, to try your suggestion --

or to be frank it seems challenging and I might just not worry about my options

for iCloud preferences, since otherwise all seems okay. Of course current

photos are not being uploading to iCloud, but I have to recognize when I am

up over my head.

So I'll try patience first.

You say in this procedure:

"If the application is the same, return the .plist to where you got it from, overwriting the newer one."

How does on return the .plist to where it came from?

Is the backing up just 'standard procedure' -- what can happen if one tries this without backing up?

I may be thick here, but where will the Library Preference folder be at that point

from desktop?