Had another look tonight and the video decoder is ff-h264 (SW) and I can't seem to change that despite changing the VAAPI options on/off.
[hr]
Just updated to LibreELEC-Generic.x86_64-8.0-devel-20160906210318-#0906-gb37a514 and it is working perfectly again.
Video decoder now says ff-h264-vaapi (HW).