contacts not syncing between devices

I'm also having this problem. Used to have everything sync in contacts. Just checked my settings and both my iMac and iPhone are on the iCloud using same account. Apple obviously broke something in a recent update, either on the OS or iOS, or both. Frustrating, hopefully it gets rectified soon, otherwise I'll start to get drift.

You need to see the article If your iCloud Contacts, Calendars or Reminders aren't syncing - Apple Support specially point 4 in the article .

The contacts should be created in Mac address book , under section All iCloud , select the contact ( use command and A keys ) , copy it ( use command and C keys ) , and paste ( use command and V keys ) to a group created .

Groups don't sync , this will stop syncing those particular contacts to the second Mac / other devices .

You can't sync Mac and iPhone , iPad with different Apple ID , for that you need to have exactly same Apple ID signed in between Mac / iPhone / iPad on the same network .

Say if Apple ID example1@icloud.com is signed in Mac system preferences and a different Apple ID is signed in iPhone ( just open system preferences using Mac spotlight ) , you will see your Apple ID signed in address .

You can change Apple ID from Mac , by signing in with its credentials at appleid.apple.com see the steps , the Apple ID of your iPhone has to be established in Mac Change your Apple ID - Apple Support , now both Apple ID are signed as same but other steps are to be followed what to do when Apple ID is changed What to do after you've changed your Apple ID or password - Apple Support 

Once done the contacts box must be turned as on in iPhone / Mac Set up and use iCloud Contacts - Apple Support 

Those contacts will be reflected in www.icloud.com see View contacts on iCloud.com - Apple Support

See this thread also Get Contacts data back on Mac ? - Apple Community

I did just notice that a test contact in Contacts I put into my Macbook air this morning showed up on my iPhone in my contacts, but the one on my iPhone didn't come over to my Macbook. Calendar seems to work, and gmail (I don't use the native mail or Safari). Not sure what they did, but I just noticed it since the latest software updates a few weeks ago.

I have the same issue now as well. I am signed in on multiple devices with the same Apple ID. My phone contacts will not sync with my MacBook.