Official comment
@DJ WhySo > As @MixMasterG points out, when setting a cue point, that location is taken from the position of the main deck CUE point. You likely didn't set the main cue to the location you're trying to store a memory point at -- it doesn't work like a hot cue and store the position of the playhead.
The reason it works with a loop is that when you created a loop-in point, by default, the deck's main cue point is now set to the loop-in location.