Problem:
When the user performs various actions regarding Events Management in Lightning, such as saving a new Expense Estimate or Event Budget, or confirming an Approval, the pop-up windows not disappear from the screen.
Root Cause:
The issue is with the EM_Event Lightning Record Page - it has the veevaEMModalLauncher added twice or more times so when clicking on any button that launches a modal, the next modal would actually open - and then when using the Save button on the first modal, it would disappear correctly, but the second modal is still visible so it looks like the pop-up won`t close.
Solution:
To fix the issue by remove all unnecessary veevaEMModalLaunchers on the lightning record page.
Related Documentation:
CRM Help Documentation: Lightning for Events Management