We have Nearby app in our Organisation that is used in a live public-facing mobile app. I'd like to experiment with some changes to the settings in the Nearby app, but obviously don't want to make these changes to the app that is used in the live solution. I spotted the Create a copy of your app button which is lurking bottom left near the exit/publish buttons:

This sounds like it's exactly what I want to do but sadly it doesn't seem to work ☹️. Pressing it lets me specify a name and location for the the copy of the app, and I get a success message when it's completed:

But if I view the app it loads the default app template centred on El Paso, not Scotland, and it hasn't retained any of the settings from the app I copied (the map, the filters, the theme etc. etc.):

Furthermore, if I try and Configure the app, I just get the blue spinner:

The app was created by another user who is the owner, but it is shared with a group of which I am a member. The map was created by a third user, again it's shared with the same group of which I am a member. I'm also an Admin on our AGOL Organisation.
Is this a known issue that the 'Create a copy of your app' button doesn't work? Is there something obvious I can do to resolve the issue or do I just have to go through every single setting in the existing app and copy it over to a new app (which I really don't want to do)?