iPhone app icons disappear from Home

When I put and arrange app icons on my iPhone's default home screen, and then put and arrange some of the same app icons on a different home screen tied to a focus mode, those icons disappear from the default home screen when I come back to it. I run newest iOS on iPhone 17 pro. The issue was present on iOS 18 and still persists. I tried to put the icons back, restart the device, change focus modes again, but it is still the same.