Here are the main reasons why campaign replication may fail.
Understanding the Issue
First, hover over the red cross to know more on the issue preventing you from replicating your push or In-App campaign.
Error Due to Language
The Default Language is not the same on the two apps: Go to Settings > General > Default language to compare the default language set for both apps.
Error Due to Labels
Make sure the labels used in your campaign are created on all the apps with the same label "CODE". To manage (or create) a label: Go to Settings > Labels.
Error Due to Targeting
Make sure the Custom Data targeted are enabled on the app where you want to replicate the campaign. Go to Settings > Custom Data on both apps or websites and compare. If you enable a Custom Data, don't forget to click to Save.
In case your targeting includes a Custom Audience, make sure the Custom Audience has been created for the app you are targeting and has the same "Name".
Error Due to the Tagging Plan
If the tagging plan hasn't been integrated with the same attributes or events on both apps or website, you won't be able to replicate the campaign.