Calendar Sync not working since 10.12 upgrade

[SysGeek]

I hope someone can please help me resolve the issue I’m having regarding Calendar data not syncing accurately after OS 10.12 upgrade.
PLEASE do not post any comments/solutions that relate to iCloud or OS 10.13, I sync via WiFi and USB if needed.
All Syncing is initiated at the Mac via iTunes.

DEVICES INVOLVED
Mac Mini
- OS upgraded from 10.10.5 to 10.12.6
- iTunes upgraded from 12.5.4 to 12.6.1
- Current Calendar app 9.0 (2155.21)
- Calendar event data on Mac seems to be accurate

iPhone 5s
- iOS upgraded from 10.3.3 to 11.4
- Calendar event data is NOT syncing accurately from Mac

iPad 6
- Came with iOS 11.4
- Brand new, setup manually
- Have NOT sync’d any Calendar or Contacts data yet, until this issue is solved

iPad 4 [stopped troubleshooting, since this device will be retired]
- OS 10.3.3
- Calendar event data is NOT syncing accurately from Mac (Same problems as with the iPhone)

WHAT I KNOW SO FAR
I’m still trying to wrap my head around all the odd behaviors that ARE happening and ARE NOT happening. The following are some scenarios that I have discovered Syncing iTunes Mac to the iPhone.

(1) ——————————
The Sync dialog in iTunes is two steps. Backup steps followed by Sync steps.
- Sometimes at the very end of the Sync step I get an error dialog: “iTunes could not back up the iPhone 5s because an error occurred”.
- Sometimes after the end of the Sync step I get: No error message, but also no backup.
- Twice during the Sync testing I have seen the Conflict Resolver Dialog: “Calendars: There are ## sync conflicts. Would you like to review and correct these conflicts now?” There are ±50-100 really old events that I resolved in favor of the Mac not the iPhone.

(2A) ——————————
- Add Event on MAC (today @ 3pm)
- Sync
- If no errors, then the Event appears on the iPhone only after iTunes re-boot, then it appears instantly on the iPhone
* I’m used to seeing the Calendar data change in real time during the Sync. In the past I have never needed to re-boot iTunes to see the fresh data.
(2B) ——————————
- Change the time of the 3pm Event on the Mac to 6pm:
- Sync
- If no errors, then the 3pm Event still appears on the iPhone and ALSO a new 6pm Event
(2C) ——————————
- Delete the 6pm Event on the Mac:
- Sync
- If no errors, then the 3pm and 6pm Events both still appear on the iPhone.

The above scenario holds true to ANY edits you make Date, Time, Notes. It keeps the original and also adds a new second, third, fourth…Event for each new edit. It seems to only want to add new Events, not edit the existing Event data.

(3A) ——————————
- Add new Event on iPhone
- Sync
- The Event does NOT appear on the Mac

(4A) ——————————
- Edit existing old Event on iPhone (move Event from Tuesday to Wednesday)
- Sync
- The Event shows only Tuesday on the Mac

WHAT I NEED
- A remedy for the Sync issues.
- Confidence that my Mac Calendar data is safe while troubleshooting.
- After the issues are resolved with the Mac and iPhone, instructions on getting the Mac Calendar/Contacts data sync’d with the new iPad and all three devices syncing correctly.

 

[Satcomer]

Sounds like the data was over ridden by one of your Macs that uploaded to iCloud! Then you have to find the Mac that has main address/ calendar plus is uploaded to iCloud to override the data! This IMHO is the danger off the centeralsystem when you have so many devices syncing and this causes problem down the line!

 

[SysGeek]

Sounds like the data was over ridden by one of your Macs that uploaded to iCloud! Then you have to find the Mac that has main address/ calendar plus is uploaded to iCloud to override the data! This IMHO is the danger off the centeralsystem when you have so many devices syncing and this causes problem down the line!

I'm not sure if you read the post, but:
"one of your Macs"...there is only 1 mac
"uploaded to iCloud"...the post clearly states in red that iCloud is not used
"danger-so many devices"... 1 Mac, 1 iPhone, 1 iPad is hardly an extreme number of devices

 

[DeltaMac]

Not sure how you can dismiss iCloud as a possibility so easily.
Regardless of the type of network connection used, iCloud is the element (the conduit, if you will) that provides the syncing, so it's reasonable to check to see that iCloud is configured --- with Calendar selected in iCloud prefs.

 

[SysGeek]

Not sure how you can dismiss iCloud as a possibility so easily.
Regardless of the type of network connection used, iCloud is the element (the conduit, if you will) that provides the syncing, so it's reasonable to check to see that iCloud is configured --- with Calendar selected in iCloud prefs.

I have NEVER used iCloud to sync or anything else
I am NOT logged into iCloud, iCloud is NOT enabled

So how can iCloud be a 'conduit used for syncing' if it's never been turned on or configured? As stated I have ALWAYS sync'd from iTunes via the 'sync over WiFi' method

 

[Cheryl]

Because iTunes syncs with your Apple ID which syncs with iCloud.

 

[DeltaMac]

Your AppleID account results in automatic setup for iCloud. It doesn't matter if you think it is not enabled. If you have an AppleID account, then iCloud is enabled. You may not be logged in to iCloud, but you might log in, and see what devices are signed in, and it will also show your various sync settings.
So, if you have an AppleID, and you have used that AppleID to sign in to your devices, you will also discover that those devices will be listed in iCloud as devices that you are signed in on.

 

[Cheryl]

And you use your Apple ID to get updates through iTunes and the App Store.