Gary, I have been waiting for someone to respond to your post because I am experiencing the same thing. I’ve been surprised no one has yet responded. So let’s try one more time.
I too have the full size iPad Pro and use it a lot when cruising. After seeing your post, I linked it to our Garmin chartplotter (7616xsv) through ActiveCaptain, and selected “Helm.” The link worked and I could control the chartplotter from my iPad *but* the display took up only a small portion of the real estate on my screen, the rest was wasted. I could find nothing in the menus or settings to get full screen. I’m pretty sure I tried this several months ago and at that time it worked full screen. If so, maybe an update has messed things up. Another theory I had was that maybe I had somehow downloaded an app meant for an iPhone to my iPad. But from what I have been able to tell, there is only one app covering both devices.
Anyone out there have any insight?