Custom team app not showing up for a user

Hello,

I created a custom Teams app using the Teams Toolkit. I see this app in the Microsoft Teams admin center, and I granted access to several users. These users also have a custom setup policy allowing uploading custom apps (not sure if this makes a difference or not). Several of these users are able to see this app just fine and run it.

Two days ago, I granted access to a new user by adding him to the Available To section in the admin center, and then installed this app on a new team and added it as a new tab in a channel. I can see the app installed along with another user, but this new user cannot. He is an owner of the team, but I don't think that matters. He doesn't see the app in the channel or under Manage Team > Apps. He tried both the desktop client and web client. I added him to another team where this app is installed a while back, but he still doesn't see anything. We tried clearing his teams cache and restarting and nothing. I've heard it can take a while for permissions to kick in, but it's been two days now so it seems like it should have worked by now. Is there something else I can do?

Thanks for your help!