To understand why the testing of in-app fails when on last step to check how the in-app looks and how is the response.
Custom Redirection - when you send a test campaign, splash screen or blank activity will open and then it will redirect to the main activity screen where it'll show the in-app but due to the above issue, the call made to the server to fetch the in-app is dropping and hence we are not able to see the campaign.
Activity Name is missing - When we are testing the in-app, it picks up a random activity from the backend to show on the screen but if the activity is missing from there, then it won't show
Key-Value Pair - It's not similar to the one seen in Campaign Creation. It's picked up from the back end, sometimes while testing the in-app if the key-value pair is missing then also the in-app will fail to show.
Activity Instance is null - This means that if there is no screen only then also it will fail to show the in-app.
You can create a test campaign targeting yourself or a group of test users.