Rabbit fur grows in cycles, so having molt patches and molt lines for long periods of time is very natural. If fur isn’t releasing, do not force it.
Daily grooming during nomting is always a good idea. One day a large area may all be attached, but the next day, it could all release. This does not mean you should be trying to yank it out that first day though – if you find yourself pulling to get fur out, you’re likely pulling out fur that’s not meant to be shed yet, which can be harmful and painful.
As for the rabbit butt, it’s common that a lot accumulates there. Most people hand pull (pull used loosely; the fur just needs a tease to come out) the fur down around the tail.
It’s nearly impossible to get all the released fur out when grooming because there is so much, but the point is to get rid of as much as you can so your rabbit is not ingesting it, which could block up the stomach and intestines.
The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.