It can happen if you edited the GPO with RSAT on a machine like an Windows 8/8.1/10 or on a server running 2012R2, even if it's a 2008R2's AD.
As for planned task if it's on a 2012R2 you edited the GPO, then it push 2012R2's option that will be unknown to a 2008R2 to be applied.
Try to create a new GPO to deploy to your 2008R2 to rule that out.
Sorry for the french printscreen, but there the display on a 2008R2, and the setting you should select to have it work on an 2008.
For reference, there is a printscreen to edit the same GPO but from a 2008 non R2 directly: