Pencil hack!
The way I get it to work is have pencil off when I open the game. Then open the game from complete close, not just switching tabs. Open Flamey’s menu right away. Then I turn on pencil and use that to go thru the menu. If it works to navigate flameys menu you’re set. Once you get it working do not use your fingers at all! That will screw up the calibration. Sometimes when the calibration gets wonky I can bring it back by going into a menu and scrolling through that for a bit, or trying to hold/drag for navigating. As long as I don’t touch the screen with my fingers I don’t run into issues. Though I do sometimes get issue if I place my other hand on the back of my iPad which I find very weird.
Also, not sure if it makes a diff but I use a off brand pencil not the Apple Pencil.