When I had my 24 hour Ph/Impedence, my gastroeneterologist asked me to challenge my GERD.
He wanted me to reflux during the 24 hours, noting the reflux episodes on the monitor, especially when laying down. I was also asked to perform all normal activities of the period, which is hard when you have a probe all the way into your distal esophagus.
When he removed the Ph/Impendence probe, I was in the same state as when I walked in (i.e. not perfect!), until restarting the PPI.
Let us know what your results are for the Manometry and Ph/Impendence. Thanks.