I'm not sure if you mean all the time, or just yesterday. Either way, that's not the case - the trains can be either way. The variation is such that people often report on gen groups which way round sets are, to help those going out to make photo's.
Yesterday and today, 68027 was at the Liverpool end of its train (I watched it leave York this evening). On Monday, I travelled from Liverpool to York with 68022, which was pushing the train.
Here's a lovely photo I've found of 68027 yesterday (quickly checks to see if photo's are allowed here)
https://www.flickr.com/photos/169014554@N07/49405927622/