I think (from my own tinkering experience) that free and workspace don't mix. So your sharing has to be free to free (personal to personal). Anything that's personal to company gets blocked.
Also, maybe the people you're sharing with have not accepted your calendar sharing invite.
Don't be sorry...Ive lost many hours of sleep over something that seems unnecessarily complex.
Let me know if you want me to try to do it for you.. or try to do what you're doing with me. I have a personal account:
arthurm...@gmail.com