Hi James,
Not saying this is “right” but just sharing my own experience of current learning- that sometimes rather than feeling one absolute direction of rising chi while rotating arm tissue out , I experience it as chi spiralling “outwards” to the extremities of the body which includes a sense of sinking – as its also going outwards to the feet, toes, fingers, scalp and beyond- not quite describable as a simply ‘upward’ direction. Then with arms rotating in- it can feel the reverse -like chi spiralling more inwards though body but also including some sense of up as “in”. Hope thats not confusing!
Sometimes I feel a downward compression and then I use rotation of the arm tissue outward to make more open space internally somehow going a sense of internal uplift (particularly connecting mind to the legs/neck which can get tight) which seems to help the sense of general flow. I think just paying attention to what is happening and being curious is good progress, and subtly grows with our practice- which keeps changing.
Regards
Nick