Still getting this bug constantly. Three ways I have saved my stupid dinos with:
1 - Hitting them with a medical health boost shot can rarely get them moving again. Doesn't work very often for me anymore, sadly, so...
2 - Tranquilising and moving it somewhere else in the same enclosure, but I have come across dinos that got so stuck I can't tranquilise them and helicopters can't target them. so...
3 - When 2 doesn't work: Save the game and reload it from main menu, should reset their ai and get them moving off to eat/drink. (or just do this first, as I do now.)
I haven't come across a point where none of those 3 options worked, yet... but who knows at this point.