User Profile

Hello, A made my project suitable for iPad en iPhone. They both have there own storyboard but do uses the same View Controller. I check on load which device is used and load to proper storyboard. I check the type of device also inside the View Controle to get the wanted result. This works perfectly on every simulator on my Mac and on my iPad Air 2, iPhone 7 and on my wife's iPhone SE gen2. But on my own iPhone Se gen2, I get an error: All the IBoutlet's that are used in the iPhone storyboard are nil. I did several reboot's, deletions of the app, etc. I also made sure that every device, Xcode and Mac OS is up-to-dat. But the error keeps coming every time. I just can wrap my head around it. Why does it work on ever device or simulator and not on my iPhone?