Hi there GregArtLeb,
If you are having issues using your iCloud calendar in Outlook on your PC, first ensure you followed these steps from Set up iCloud Mail, Contacts, and Calendar in Outlook on your Windows computer to add this calendar:
1. On your Windows computer, open iCloud for Windows.
2. To set up Contacts and Calendar, select “Contacts and Calendars,” click Apply, then follow the onscreen instructions to set up Outlook.
3. Note: If you see “Mail, Contacts, and Calendars,” selecting that option also sets up your iCloud Mail account.
4. To set up Mail, sign in to Outlook using your Apple ID email address and an app-specific password. See the Apple Support article Using app-specific passwords.
If this is how it was set up, then follow these specific steps from If you can’t add iCloud Mail, Contacts, or Calendars to Outlook (that you've already looked over) next since they can resolve issues like this:
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.
If this persists after following those steps, then reach out to Microsoft Support next. They would be the best equipped to look into this unexpected behavior further. Connect with them here: Outlook help & learning
Cheers!