This will only be resolved with time when baby is more familiar with the helper, but you can help speed it up by having helper interact with baby as much as possible, play and talk to baby, or just have helper sit around when you're playing with baby. Some people say it also helps of helper carries a piece of mummy's clothing so she smells like mummy, but it didn't work for me 😅. Don't worry I'm sure it will improve in time, soon you will feel sad if baby's too attached to helper haha
May be due to unfamiliarity, LO needs to get used to the touch and smell of helper