This sounds like a conversation for you and your manager. I’ve had a few with my team that have resulted in different solutions for different people.

With one we established a monthly 1h call for her to explain where she is stuck, what she has tried, and we brainstorm how to get through it. This is separate from our usual weekly check-ins and focuses on issues related specifically to complexity and ambiguity.

With another, he created a list of what she thinks needs to happen and puts together ideas on how to get through it. I review it and then give him feedback. He liked this as over time he built confidence on his ideas as my feedback more often than not was “exactly what I would try, go for it”.

Finally, sometimes is about reducing the work load on that team member until they get a good foothold and slowly start adding more.

Shot answer, no one solution or easy path, but communication with your manager and hopefully a good manager is your besy bet.