eMail address for iCloud contact is on the Mac but not on the iPhone or iCloud.com

Firstly, the "Contacts box" has been checked in the Preferences all along.

As you suggested, on the Mac, I created a test-contact under All iCloud, & another test-contact under All on My Mac. Then I logged into iCloud.com & found the first contact, but not the second (as expected). I also did a Refresh Contacts while logged into iCloud.com, but saw nothing different later.

Any more ideas please?

My Mac is a mid-2010. I know I am stretching its life to a snapping point! I am waiting for the coming M1X models. The OSX on my old Mac is 10.13.6, as higher versions are no longer supported.

As for creating a new admin account, I didn't catch what I should be checking for & the objective. Please elaborate.

Hi there. I stepped through your recommendations: iCloud has been checked as the default Contacts account all along. I set up a new administrator account, made sure iCloud is the default account in Contacts, pulled up the details of the that contact whose email address was missing when the problem first arose, & can confirm, the email information is still missing from the iClouds contact in the new administrator account. So, I suppose, we surmise, my original normal account, which also happens to be an administrator account is not corrupted, at least insofar as the missing email issue.

The Mac apps include Malwarebytes, Omnidisksweeper, & no cleaners or VPNs, of which only the first - Malwarebytes - has been running in the background in both original & new admin accounts.

Thanks for the reply, but the question here is why a contact, indicated as an iCloud contact, does not show the email address on an iPhone or iCloud.com, but does show the email address on Mac.

Thanks. I refreshed contacts on iCloud.com as you suggested. The missing email address, which does show as iCloud on the Mac Contacts, did not appear in iCloud.com. Any other ideas?

Thanks again for your help & please do bear with me. I just went back to my Mac & checked the iCloud contact details for that contact, & see the email address shown. If as you say, had I saved the email address in the MAC address book - and not iCloud - wouldn't that address be missing from the details when I looked only at the iCloud?

Hi there. I removed Omnidisksweeper & stepped through the instructions. I don't see anything different on the issue of email address for the iCloud contact missing from iCloud.com but visible on Mac's iCloud Contacts. I noticed another anomaly for which I am attaching a scan here:

First, note this has all been related to a contact named Chad with last name initial "S". On my Mac (obviously, as I see the email address), I noticed a card tagged as "On My Mac" as Jordan with the same last name as Chad's. But oddly, Jordan does not appear as a contact on the listed contacts (see attached image). Another clue is that a Jordan, with a different last name, used to be the original contact for this business, which was edited to Chad when Chad took over Jordan's position. So I wonder if there is some corrupted record that occurred when editing. So, could this be the issue, & if so, is the fix just a deletion/replacement of the contact altogether. Also, if this is a corrupted record, how far does the corruption go; i.e., just Chad, or more contacts? Lastly, how does such a corruption occur & what can be done to avoid it in future?