Here's a video of my problem:
https://youtu.be/svCoU0OCsUo
In the video, I show that 4 textbuttons in a difficulty select GUI I made all have modal set to true, one of them covering the entire screen. This works fine with my other GUIs, however this one GUI still locks the mouse cursor when in first person mode. Although my mouse in the video doesn't show up, the mouse is locked whenever I enter first person, even though the modals in the textbuttons in the GUI are all set to true. Why is it doing this?