In the life of a Problem record, there are opportunities to click the Re-Analyze button and move backwards in the lifecycle.When you click the Re-Analyze button, what state is set on the problem record?
You can reanalyze the problem even after it is closed by clicking Re-analyze. The state of the problem changes from Closed to Root Cause Analysis. The following problem management properties controls who can reanalyze the problem:
https://www.servicenow.com/docs/bundle/yokohama-it-service-management/page/product/problem-management/task/resolve-and-complete-problem.html