planner-copy-or-move-region misses the first marked line

Hello,

I have some trouble with the planner-copy-or-move-region function. When I
try to move a marked region of tasks, it misses to move the first line/task
of my region. I start marking my region with C-SPC at the beginning of a
line then go down some lines and call planner-copy-or-move-region. A lines
are moved to a new date but not the first.

So it is some kind of off-by-one error, but I was not able to find it. 

Anyone else with this problem or have I broke my setup?

Regards,

Philipp