"Is Planny Pro required?"
No. Planny Teamwork requires iCloud Sync, but this is already included in Planny Teamwork
"I don't see any changes"
Make sure that Cloud-Sync is enabled. If your subscription expired one time, Cloud-Sync is automatically disabled.
"I don't see any of my invited people"
Make sure that they activated "Find my via iCloud", else you can't see them.
"My friends don't have a profile picture or name"
They can set these up in the Productivity screen. Note, that these changes will take some time to be visible.
Are there any other bugs? This feature has been tested over months, but still there can be small issues. Please provide a bugreport so this issue can be fixed within hours.