Github App transferred to Organisation not showing "Install App" etc

I am trying to setup a Github App to give some scripts limited Admin rights to some repos in an Organisation. The Organisation is (I believe) under an Enterprise account - we are using this currently instead of having an Enterprise server. I have created the App, transferred it to the Organisation, and one of the Organisation Admins (which I an not) has set me as the manager. So far so good. However, although I can see the App in the Organisation Settings, there is no “Install App” button. Also trying to use it in scripting gives 401 (A JSON web token could not be decoded) errors trying to get hold of a “PAT” for the app - even though the Admin has installed it into the app.

There is obviously something wrong but I’m at a loss. Does anybody know of some extra logs that can be looked at or have a suggestion on how to approach this. We’ve tried deleting the app and retrying - no different. I should say this is the third app I’ve created for transferring into the organisation this way - so far it has just worked.