Per feedback from certain users regarding the removal of the User Task Report in 18.1, I have designed the following standalone app which should work in most environments, is geared towards admins (or users with "designer" privs and appropriate permissions to process instances), which creates a new "Reports Tab" report to reveal tasks for any arbitrary active user. The report offers quick access to the task itself as well as to the process instance.
Update: This tool has now been added to the AppMarket. If anyone has used it and likes it so far, please go to the AppMarket listing and give me a star rating or 'like' :)
The following app package is all-inclusive, except for certain Appian Common Object rules which I'm including in a separate patch. (Updated version: renamed to "Advanced User Task Report".)
8875.Advanced User Task Report (18.1 - 2018-07-23).zip
Update: 19.3 version using the new read-only grid and other enhancements:
Advanced User Task Report (19.3) - rich text grid updated (v2).zip
The needed Appian Common Objects, for environments which don't otherwise already have them (this would need to be imported first):
4010.Admin User Task Report - Appian Common Objects Patch (18.1 - 2018-05-29).zip
Discussion posts and replies are publicly visible
Update: This tool has now been added to the AppMarket as well as Shared Components. If anyone has used it and likes it so far, please go to the AppMarket listing and give me a star rating and/or a 'like' :)
Also I plan to make periodic updates / bug-fixes as needed, so if anyone has any feedback please feel free to drop it here and/or on the AppMarket page.