What has caused blockage in drain hose pipe?

If water is too soft, it can affect a detergent’s dissolving ability, and the rinsing efficiency of the washing machine. If your water isn't especially hard, and you use a good quality detergent as well as using the correct dosage for hard water (washing machine detergent contains water softener) and then add anti limescale tablets, which also soften water, you could get water that's too soft for washing and the detergent may not dissolve properly.

As for which is best? I personally think good old fashioned washing machine powder is best. We were happy enough with it for decades, until washing machine detergent manufacturers started trying to come up with innovative ways of getting ahead of the competition. We then had, liquid detergents, then tablets, then tablets with liquid pouches etc. etc. Most of these products are aimed at our lazy side. They seem more convenient to use. They save us several seconds etc. None of them claim to wash any better, they are just more convenient to use or store, and we usually pay extra for convenience.

However, cold fill washing machines can have problems dissolving some powder detergents thoroughly, so liquid could be better there, the same applies if you have very low water pressure which leaves un-dissolved powder in the soap dispenser.

Also, if you have an extra rinse option I would leave it selected for all washes which would help.

This may be of interest, particularly the section about doing a service / maintenance wash - What happens when you only use 40° washes?