From the query I understand that you are resolving few child cases after which you are trying to resolve the parent based on a condition "pxCoveredCountOpen" which is sometimes not zero and hence parent is not resolved.
Quick question -
1. How are you trying to resolve the child case you are referring here in the use case?
2. While resolving the child, did you face any Lock errors for parent in logs?
3. What is the value that you observing in the clipboard for pxCoverCount, pxCoverCountOpen and pxCoveredInsKeys?
4. On click of button, which activity/activity steps are used to resolve the parent?