Customer reports, they are not receiving push notification into their mobile device. They can see, it's getting captured in the logs.
Release or Environment
OOB REST Message "ServiceNowMobileApp Push" (ded0e522ff1231009738fffffffffffc) which sends this notifications is missing in affected instance.
Please XML Export this REST Message from your other instance where it's available along with respective Resources and XML Import it in affected instance and it should fix the issue.
NOTE: In case you don't have any other instance, you can always find it in an OOB developer instance.