Cannot use (Fn+)F3+B for Hitboxes

So for the most part I have gotten accustomed to having to press the function key for F3 things. From my knowledge of using this way, all these following Fn+F3 shortcuts work;
+A - chunk reload
+C - locaton copy / manual crash
+F - Increase render distance by 1
+Shift+F - Decrease render distance by 1
+G - Chunk borders
+H - Advanced tooltips
+N - switch gamemode
+Esc - pause
+F4 - new gamemode switcher

However, Fn+F3+B (and a few others) do not work;
+B - entities shown
+P - toggle pause in background
+T - Texture reload
+Q - Shows all commands
+I - block/entity data copy

Need some help