Elidibus (with Xehanort's player permission) attempted to place a tracing spell on Xehanort. It would have been tracing his soul opposed to his body. I know this doesn't track past the barrier but does it give the vibe of being dispelled or 'possibly still present but signal jammed'.

(His aim would have not so much been 'can I track this beyond the barrier' as 'if I run into a Xehanort again I will know which is the one I knew' or 'if we ever locate where these souls go, maybe the ping of the trace will indicate they're around')