Books app and Apple Pencil pro

My Apple Pencil pro has a squeeze feature which pops up a palette (markup menu) which allows us to switch tools. If I'm using the pen and I double tap. Then it switches to an eraser on the notes app. But when I'm on the books app the double tab will only switch between pen & eraser if i select my tool from actual markup (and menu not the one which pops up with the squeeze feature). Additionally the minimized markup menu (the little circle with your current tool which sits in any corner of the screen) doesn't appear when I select the tool by the squeeze-menu but it does when one selected it from the actual markup menu. And this is only on the books app...