Runner beans always climb, they also need a lot of water.

You may have bought something that wasn't as labelled, that happens, but I'm surprised the nursery didn't advise you that runner beans need a deep trench filled with lots of good composted material , then back filled and the beans planted in it. I'm not at all sure what the success rate will be with runners in pots, special veggie compost or no.

Thanks for all comments received. We have grown runner beans in large pots for the past 4 or 5 years and always had good yields. Indeed, we presently have another large pot containing runner beans (from a different source) that are climbing happily up the canes.
That's why we are unable to understand what's going on with the yellowish ones as they appear quite healthy otherwise.

Are you using a different compost with the stunted ones?

If its the same compost as all the other pots, I'd be returning the plants to where you bought them and asking for a refund - sounds like they're either not what they should be, or are dodgy ones.

I do not know about yours but I can confirm there are dwarf runner beans. I grew them once but I prefer the tall climbers because they yield much more. Yours may have suffered a check due to sudden exposure to cold weather or by remaining in very small pots neglected for a long time.

I don't know about runner beans, but if they are like pole snap beans, once they have been sitting in the plugs for a couple of weeks, they never seem to recover.