Easyforms: show revision history does not work correctly

In the latest and previous versions of Easyforms, as used in a client project, I encountered a problem when I used the Revision History functionality on a easy-forms document (which had several revisions).

When I select an earlier version, the content of this version was not shown
When I choose "Restore"/"Plaats terug", all entered data (field labels etc) are lost.

I can reproduce this behaviour in the development-, test- and production site.

If required, I could provide logging data