Jalkrin

Did someone answer you question regarding the Prof Ivy and Porygon thing? If not here's what I did: First when I went back I got the problem, that while passing the little sand isle right before valencia, I got transformed into Delia and I was portet into the second floor of the pokemon center. What I did then is walk around but I found nothing, just like you, then I headed back onto the water right before the trigger that made me look like delia and retracked what I did. So go back to valencia and enter the pokecenter, leave the center and make your way to prof ivy's lab. From that point on everything worked for me :/