Hm, that’s very odd, it almost looks like macOS is interpreting any sort of click on the game as one outside of it, and minimizing the game accordingly. The only change made recently to this sort of thing was one relating to multiple monitors, do you have more than one monitor connected?
Pressing option+enter should put the game out of fullscreen mode as well, which should help.
I worry that this would lead to very tedious gameplay where players would feel the need to keep track of what things the book has already cast so they can plan around the new likelihoods, and eventually the garunteed final effect before a new rotation starts. The book is also supposed to be quite random, which does include possibly rolling the same effect multiple times.