I am having trouble changing maps with Select a Map in Instant apps.
I used the Select a map to change from a dev map to the final Map already in Production. The Select a map at first appeared to change the referenced map within Instant apps. However the updated map does not seem to be available for other instant app components.
I am unable to add map layers under add search source for the Search Bar. The Map option does not show a list of layers. And the OK button is disable.

Selections of layers to include in the Layer List on the Sidebar tab are ignored. The Layers tab when instant apps is launched shows all the layers in the map.
It appears I need to recreate the instant app. Which won't take too long, it does mean the url link will change.
Being able to change the map and retain the same URL is nice feature, and helps prevent users from going to an older version of the app.