Modified By Field is not capturing the Value

Product Version: 12.2.1.4

We have a custom field called Modified By, which is enabled in info and Update page via rule.

Activation condition is like- (dpAction like "Info" or dpAction like "Update")

I have added the field in the rule and set it as- <$dprDefaultValue=#active.dUser$>

The issue is, whenever we are going to update a document for the first time, the field Modified By captures the user value perfectly.

Now, if we want to update the same document with a different user(having the same access right like the previous user) or using weblogic user the field Modifed By still holds the previous value. It's not capturing the current value.