Hi, good day.
I'm working with the example: 6_BrowsingPois_4_ReloadingContent of wikitude-sdk-samples-master.
I tried the example and it works fine, the points of interest appear.
Swap the URL POIDATA_SERVER: "https://example.wikitude.com/GetSamplePois/", by the URL of the web service type resfult created with the Google App Engine.
When I reinstall the app and run it it displays Invalid web-service response.
In the example that when you access https://example.wikitude.com/GetSamplePois/, the JSON array containing the information of the example interest points appears.
Did you have a look at the documentation here regarding how to retrieve data from a Web service? Please, make sure that the server returns valid JSON and it is escaped properly (e.g. special characters in POI name…).
If you are still experiencing issues then please let me know,