Hi! I have a problem with "fix position when scrolling" on desktop prototype and mobile. Help, please!

Hi, I am studying Ux/Ui design and I use Figma for the first time. For the final project, I have the following issue: When I make the prototype, the mobile preview is ok, but when I want to test it on mobile version, the bottom navigation bar is missing. Any ideas how can I fix it? If its matters, the frame is for iPhone 14 pro max, now I am testing it with iPhone 13, but there is another people who are testing with the same mobile which is the frame. I will send you a screenshoots if you didn’t understand me right, Thank you!