Might be order of operations. The screen shots provided by @animisha45 have the first step to change the index value of the element dragged, then second step is referencing that previous steps result and it’s index, which likely had already been updated.

You might want to setup a custom trigger, which is with action to make changes to list, and in the flow, trigger that custom first step (this is will make it run and complete before next step) and in the next step, make changes to the dragged item index value.