There could be a number of reasons why this could be happening. Unfortunately, a few users have reported not being able to use the F3 key in Minecraft. Basically, the F3 key enables the player to show the debug screen on his game. The F3 key is used in Minecraft to learn all the important elements in a game, such as your coordinates, or information about the biome that you currently are in. Each function key may have a completely different use than the other.
Similarly, games like Minecraft feature the use of function keys as they allow users to perform certain operations on the game in a quick manner. For instance, a function key may be used to increase the brightness of the program, but at the same time, it may also be used to save something in an application. Function keys are present in every keyboard and are used to perform certain operations on a computer or a program.
