Carpet cleaning and dog hair

My X50 doesn’t pick up dog hairs on my dining room carpet and seems to just collect them into a dirty wet bundle at the side of carpets. It struggles with a thick sculpted hall carpet too. I have re mapped once but find the carpet features baffling. I have had to manually clean out dog hairs clogged in the filter but that is clear now and it doesn’t seem to be sucking them up at all.