Since a recent JSD version, Validator error messages don't show up anymore in the error box at the top of the JSD request creation screen. This is due to a regression in JSD.
We can fix this for error messages related to a field (e.g. Field Required Validator, or the Scripted Validator using the "For field" option). But if the message is not associated to a field, it will not be displayed (unlike in previous JSD versions - e.g. 3.0.11).
We are using atlassian-servicedesk-3.12.2-x64.