I think Harry's issues are two-fold.
First, he's been pretty unlucky thus far in some of his shooting. Statsbomb lays the case out today pretty well:
Fun, Order And Klopp: Week 9 in the Premier League
But for those who'll go tldr, basically Harry is not shooting quite as much as last year, and has had an abnormally small number go in.
He's taken 11 shots. Of those, it's most likely that at least 3, maybe 4 should have gone in. They haven't. That's partly just randomness, I think, and we'll see that change in future.
I think partly though, his problem is that he feels he needs to be scoring more, and is taking some shots which he shouldn't be. Teams now identify him as a threat, and they also know he's going to be trying shots when he should instead be making the pass to players in better shooting positions. Since they know he won't make that pass, defences are comfortable in swarming him and cutting off the space he needs. Unless other plays pass to him less and shoot more themselves (making the defence have to stop focusing on Harry), or Harry himself passes more (forcing the defence to do the same thing, and give him more space for his own shots), he's not going to get the chances he needs.
I think the solutions is between these two points. Harry needs to shot less and pass more, to force opposing defences to give him more space, and he needs to relax as the shots he is taking will start going in more in the near future.
I would still give him a rest against Anderlecht, as too many minutes too early in a year will make for massive fatigue issues later.