Oh yes there is need to break up the stacks. Usually I sneak up from behind them to throw the berries. I don't get too close so my berries land behind the lox. This causes few things;
1) the lox turns after there is berries available behind it
2) the lox sees/hears me and comes to investigate
3) the berries are left at the ground
4) I hurry to high ground with the lox in tow
5) the berries eventually despawn
6) keep dropping those berries one by one until tamed
7) currently sitting 4th night in a row on top of rock, taming 3rd lox
In any case this is how I manage to tame the beasts but what about the bug/feature, does the same thing happen to you?