Issue: Cannot Share Agent to New Editor in Copilot Studio New Experience

I dont know if this is still relevant, but there is a workaround. I tested it and it works in my tenant:
Original Author: https://www.powertricks.io/sharing-and-deploying-copilot-studio-agents/

In Short:

• Every Agents that gets created in the Env has a Team automatically created with it (Team name = agentId_1)
• Adding a User with ENV-Maker role to that Team grants them Edit access to the Agent
• Removing the ENV-Maker Role broke the access to that agent in my tenant
• There might be a lesser privileged role that might still work. 
• The important DV Tables seem to be bot and botcomponents where orga CRUD access is required

Hope this helps!

In the current new experience, when you share an agent you can grant view/use access pretty easily, but the Editor role (which allows collaborators to edit, configure, share, and publish the agent) isn't always surfaced in the same way as the classic experience. The root cause is that sharing for collaborative authoring has a hard dependency: the target user must have the Environment Maker Dataverse security role assigned. Without it, the editor option either doesn't appear or fails silently. 

What you can do right now:

1. Use the "Classic Sharing" fallback. In the Share panel, look for the three-dot menu (…) and select Use Classic Sharing. This brings back the familiar experience where you can explicitly assign Editor rights.
2. Ensure the right Dataverse role is in place. The person you want to grant Editor access to needs the Environment Maker role in the Power Platform environment. If you're not an admin yourself, ask your system administrator to assign it. As an alternative, the System Administrator or System Customizer roles also work. 

On the roadmap question, Microsoft hasn't published a specific release date for surfacing Editor rights natively in the new UX sharing panel.