Calendar will NOT share - invites Disappear

As the person who recommended that our company use Apple's iCloud system for work, I'm getting egg on my face for suggesting that we switch from Gmail/Google Calendar to iCloud. The boss was using Google Calendars with no problems, but liked the idea of using the Apple Ecosystem. But we CANNOT get the Calendar sharing to work on all accounts.

We all have iPhones 6s and iPad Pro's, using iOS10. I have created 4 separate iCloud accounts for each person - user.company@icloud.com, so everyone has their own calendar and mail. Reason for sharing is so the receptionist can enter Appointments for the team. For some "strange" reason, ONLY one of these accounts will share. I have tried it on the iPhone, iPad and iCloud.com. I have logged out, logged in, reboot, reformat, reset and etc. No luck. So, here is what is happening:

I go into Calendar on my iPhone and select Calendar at the bottom center.

I select EDIT.

Then under iCloud I select my calendar, which I renamed to may name.

Then I select SHARED WITH, then Add Person.

I type the name user.company@icloud.com

Click ADD.

I can see the name under SHARED WITH listed as Pending (view & Edit).

Then at top right, I click DONE.

The screen goes back and I see the name and then BAM...it disappears and NO INVITE is send and etc.

I must have over 20 hours invested into trying to get it to work, reading forums, posting questions, and NOTHING has worked so far. Boss not happy, me frustrated.

It simply DOES NOT work. And my searches reveal I'm not the only one with this issue, going back to 2010...seriously?

Any ideas and suggestions would be appreciated before we switch back to Google.

😟 😟 😟 😟 😟

PS - next time I'll keep my mouth shut.

It just doesn't s