UWL popup does not close automatically

Hello

Issue description:

Scenario 1: user default language is "NL" (set from ECC system). User clicks on UWL list, popup window opens up with the task details. User perform action (like, hold, reject or approve). Once button is clicked, popup window is closed automatically. This is as expected behaviour

Scenario 2:

Same user default language is now changed to "EN" (set from ECC system). User clicks on UWL list, popup window opens up with the task details. User perform action (like, hold, reject or approve). Once button is clicked, popup window does NOT closed automatically. Instead, popup window becomes blank.

This is the issue. Could you please suggest what could be an issue here.