Where a course is repeated throughout the year with multiple groups of students, it's useful to be able to filter Feedback surveys by date (eg to the month or quarter that each cohort ran). While the responsetime information field works perfectly if Feedback is not anonymous, when it is set to anonymous the date field changes to 1st Jan 1970.
As far as I can tell from issue MDL-37800 - which was a request to include the information fields for download, this was deliberate though the testing instructions aren't clear.
Can the responsetime field be made available to anonymous feedback export? Adding it to a Feedback is an institutional decision based on information need.
If that isn't possible the settings should be changed so that it isn't possible to add the responsetime field to a feedback if it is set to anonymous - it's just confusing (especially when the correct timestamp is displayed when you answer the questions).
As a third (and least prefered) option - can the 1970 Unix timestamp be replaced by a more informative response such as 'anonymous submission'.
Thanks, Gordon.

edited

Response time is hidden in case of anonymous feedback on purpose. In this issue we removed this option for the anonymous feedback.
Response time does not make much sense for non-anonymous feedback either because the submission time is recorded and displayed anyway, MDL-54024 is created to consider removing this option completely. In this issue the default value for "information-type" is changed from "response time" to "course"