If trying to resume a program later that was part watched/time shifted while it was still recording the resume recording option in the menu will be unavailable and the watched/part watched circle indicator will be full white indicating an unwatched program, this is a bug.
If there is no resume option and you know you've part watched it then don't select any options just press the back button so that the required recording is highlighted in the recordings list and then press the PLAY button and the program will resume where you left off.
Maybe this should have an entry in the FAQ.....
'How to bypass the lack of resume bug and resume all recordings with the least amount of button presses' ?
Answer.....
'Highlight recording in list and press the play button'.