difficulty getting starter going

Hi all. I am on my second round of trying to get a starter going. The first one flopped and online friends suggested using filtered water and a higher quality of flour.

This time, I am using the recipe on King Arthur flour. I started with Bob's Red Arrow rye and filtered water. Since the second feeding, I've been using King Arthur AP flour and the same filtered water. Although the first day with the rye produced bubbles and it doubled in size, it hasn't done anything since I began feeding it with the AP flour. Nada. I'm feeding it twice a day, though it doesn't move / change between feedings. I'm on the 5th day of this process. Any suggestions?

Thank you!