In inventory, with the guidebook open, at a GUI Scale of 5 or higher in full screen, I cannot select the top right three inventory spaces.  If guidebook is turned off I can access all of the inventory.  Setting the GUI Scale to 4 or lower this is not a problem.  Attached screenshot the mouse pointer is in the center of the top right inventory slot.

My workaround is to push F11 twice, then I am able to access all of the inventory items with the guidebook open.