If I have a list of tasks that more that's longer than the screen, I can't drag a task higher than the task currently at the top of the screen. I have to drag it as high as I can, then scroll up, then drag it again.
In the mobile apps, if I drag a task to the top of the screen, the list starts scrolling so I can drop it higher up. This should be implemented n the web interface too.
My workaround is to click the star to mark the task important, which jumps it to the top, then unmark it again. That's helpful, but still a pain if I don't want it at the very top.