If we query the "options" table before installing RU2, we find that the option with ID 6025 is named "casc_impersonate_user". After completing installation of RU2, the option with ID 6025 is named "get_plain_text_timeout". Where did the "casc_impersonate_user" option go?
The problem can be identified by executing the following query both before, and after installing RU2:
SELECT * FROM options WHERE id = 6025
Service Desk Manager all versions up to and including 17.4 RU1
This problem will be fixed with the upcoming release of Roll Up Patch 3 (RU3) for 17.4. If a test fix is needed before the release of RU3, please open a support case and reference this KB article.