There are two solutions:
1) Manually update the Qlik Sense Repository (Qlik Tips: Promote a Qlik Sense sheet from Community to Approved), or
2) Copy the Binary File from the Apps folder, rename the Binary file with a .qvf extension, then import the renamed file.
The Sheet Approver enables users to approve published sheets in an app, thus, making them base sheets of the Qlik Sense application. In addition, it's possible to un-approve sheets as well and push them back to the community.
This may help to sheet import into another app.