Apple Calendar using iCloud and Exchange has sync issues across devices

Hi DNArizona,

Based on what you've shared the best steps to take can be found here: If you can’t add iCloud Mail, Contacts, or Calendars to Outlook - Apple Support

iCloud Contacts and Calendars

If you need help using your iCloud Contacts and Calendars with iCloud for Windows, try these steps. 

Turn iCloud Contacts and Calendars off and back on

1. Close Outlook.

2. Open iCloud for Windows.

3. Deselect the Contacts and Calendars checkbox and select Apply.

4. Wait a few seconds. Select Contacts and Calendars and select Apply.

5. Open Outlook.

Make sure that the iCloud Outlook Add-in is on

The iCloud Outlook Add-in transfers your content between iCloud and Outlook. Follow these steps in Outlook 2010 and later to check and turn on the Add-in:

1. Select the File menu.

2. Select Options in the left panel.

3. Select Add-ins in the left panel of the Outlook Options window.

4. Look at the list of add-ins in the Active Application Add-ins section. If the iCloud Add-in is listed under Inactive or Disabled Add-ins, make sure that Com Add-ins is selected in the drop-down menu next to Manage at the bottom of the window. Then select Go.

5. Select the iCloud Outlook Add-in checkbox, then select OK.

6. Restart Outlook.

Make sure that iCloud isn’t your default account in Data Files

When iCloud is set as your default account in Data Files, your data won't sync between your devices. 

1. Select File > Info > Account Settings > Data Files. 

2. If iCloud is listed as the default account in the Comments column, select a different account.

3. Select Set as Default.

After you've tried these steps, restart your computer. 

Should the issue persist we recommend reaching out directly to Microsoft support!

Regards.