Can I please ask a few questions.
1. Technically (not a question) Agents aren't setup to do this, for several reasons but..
a) in this instance those app registrations are only good for the one tenant (which is why it works on the one)
b) I would need to understand how your actual multi-tenant configuration is setup (which is more an Azure situation not copilot), can still help, but will try
c) what channels are you publishing this on? technically an anonymous open one shouldn't be a problem
d) what authentication are you using?
e) what Tools / connectors etc are you using?
2. Primarily you are usually going to need a master agent so that you can route to the child agents. Making sure to publish to Channel that support this, such as Teams or some internal Web app, or of course a completely Open (as mentioned anonymous agent). the other issue is, do the people who will use it, and depending on your connector configurations (Agent flows / power automate) do users in different tenants have access to the data and or authorization to the end points that the Agent will use regardless.
Also this is Copilot Studio, NOT Copilot Studio lite correct?
3) Lastly and maybe I should have put this first, Make sure that your App Registration is setup for Multi-tenant, by default it will be single which would make this fail. Make sure you have the proper Redirect URLS.
Make sure to give the proper scopes openid, profile and user.Read
Its recommended to Expose an API, with a custom stop under Expose an APi, add in admin and user consent for the scope
For identy types, makes sure you enable Managed, Single Tenant App, Service accounts or client credentials with a client secret.
I also use the Power CAT Copilot Studio KIT (well all of the CAT stuff really lol, but specifically for Copilot as this can help you too).
I believe #3 s really your issue soI should have written it first, but brain dumps come as the come lol
If these suggestions help resolve your issue, Please consider Marking the answer as such and also maybe a like.
Thank you!
Sincerely, Michael Gernaey