I have found Elk in spots in the past that every year I go there I’m into Elk . Then in the same spots a few years later I can’t even find a track what happened the the Elk ? Did they find a better spot to live ?I'm not sure unpredictable is the term I would use. IMO, They are actually very predictable.
If you give a frame of reference, ie- the general area and the season/time of year...folks can give you a better answer.
Example; I've seen elk in early archery season traveling all over the place [rut]...and I've seen big bulls hunker down in a 50yd square area hardly moving in Northern Arizona after the rut during rifle season.
Elk are very susceptible to hunter pressure...changing their behavior and finding those out of the way areas when hunter pressure gets high.