DRG Heavy Thrust -> Ring of Thorns

Ring of Thorns is supposed to get a combo bonus from Heavy Thrust, but I see this bonus applied very inconsistently. I seem to get the combo bonus more often when I use Heavy Thrust without the buff already active, but even then it isn't 100%

Is this bugged, or am I missing something about how they're supposed to chain?

Ring of Thorns only gets the proc if you also get the side positional that Heavy Thrust has.

Thanks!! That was bugging the crap out of me!!