Old post but we have been experiencing a similar issue where our private cloud app instances are not always receiving a valid license upon startup. Mendix support provided us what appears to be an undocumented runtime setting "License.CallHomeRetryInterval
". They told us the value is in seconds and that setting it to 10 should be safe. The default value is 60 minutes.
We changed our application to 30 seconds and so far it seems to be working without issue.