I'm not sure if I'm missing something on my Redmine installation, but when I go to Gantt view and when I'm using the Sprints module, all issues associated with a particular sprint, should appears below the sprint.
In my case, the appear tottally disassociated.
See attached screenshots
RE: Gantt structure - Added by Felix Schäfer over 9 years ago
IIRC the issues and versions are listed in whatever order you have set in the filter at the top, the default probably being by ID or something. There's a gantt rewrite in trunk, though I'm not sure what has changed in it (I don't use gantt myself).
RE: Gantt structure - Added by Bernard Steens over 9 years ago
I have the same on my enviroment after upgrade to trunk revison 4226, with my old version 3779 the subtasks in gantt were almost funtianal.
I added an issue ( #6693 ) for this problem.