Reinitialized. And actually went back and tried again to installed the latest firmware. (This time there was no "Invalid" message.) Then reinitialized again so that I did all your steps correctly. Unfortunately yes, the app keeps quitting on me when I try to save to the pedal.
This is strange. So it's just the app and your H9 works fine, right? When you click a preset in H9 Control, does your H9 load it? Can you save the preset on your pedal by long press the PRESETS button?
Have you ever tried connecting to your H9 on your phone? Does this issue happen on other devices as well?