I am trying to debug an iOS application that uses storyboards. When the first problem is displayed, this is correct, for example:

When I go to the next scene by pressing one of the buttons, for example, "Any category", and then move again, the navigation buttons will disappear like this:

I could not find the obvious reason for this change. Is there something in particular I should look for that can change the navigation bar? Perhaps there is some automatic processing of the storyboard process that should be turned off?
Here is part of the storyboard to provide context:

, "" segue, , , , .
viewDidLoad:
UIBarButtonItem *backBtnItem = [[UIBarButtonItem alloc] initWithTitle:backArrowString style:UIBarButtonItemStylePlain target:self action:@selector(backBtnClicked:)];
self.navigationItem.leftBarButtonItem = backBtnItem;
self.navigationItem.leftBarButtonItem.enabled = YES;
:
-(IBAction)backBtnClicked:(id)sender
{
[self.navigationController popViewControllerAnimated:YES];
}