If your agent doesn't work in Teams, there are only a few reason that would stop it (and you didn't mention for whom it didn't work so I will assume you as well)
1. You do not have the proper licenses for Teams
2. You do not have the proper permissions on Knowledge sources, for whomever it doesn't work for
3. There are DLP or other Tenant Level or Environment Level configurations made by an admin or defaulted too (like in some GOV Clouds) that block it
4. You have a connector that does something that is not allowed in your tenant / environment and or the permissions block it, so validate by going to powerapps.com or powerautomate.com and select ...More, then Connections and verify each connection used by any Agent Flows / Tools etc
5. Depending on your AI setting, if you use topics and plenty of other things, again it goes back to what your agent USES to do what it needs validating independently that each part works.
Without seeing your agent and knowing what it even does, or how, those are the standard places to look first.
Lastly, there is always a slim chance that its simply cached badly. When it deploys, assuming it either existed or didn't before, deployment can take time, it may not be immediately it can even take hours or a full day.
So you may just need to give it time.
If these suggestions help resolve your issue, Please consider Marking the answer as such and also maybe a like.
Thank you!
Sincerely, Michael Gernaey