UIBarButtonItem working but not visible with Xcode11 and Xcode12

System Font Symbols have been changed since their introduction, so they can be referred as SF Symbols 1 and SF Symbols 2, where SF Symbols 1 are part of SF Symbols 2 (which support multicolor symbols) and some have also been changed in detail.

Some symbols (actually a lot of them) have been available even before iOS 13 but in general the Docs say…

SF Symbols are available in iOS 13 and later, macOS 11 and later, watchOS 6 and later, and tvOS 13 and later.

So the specific symbol arrow.clockwise you try to use is part of the SF Symbol 1 Collection and is one of those who have been available even before iOS 13 as Refresh Symbol. But as they are re-introduced as SF Symbols you run into trouble here. In targets below iOS 13 they (some) appear as part of UIKit’s Controls and above iOS 12 they are System Font Symbols that respect multiple parameters of your UI, like darkMode, lightMode, anyMode, FontWeight, localization and so on.

From Apple Documentation.. Creating Custom Symbols

If you need a symbol that isn’t provided by SF Symbols, you can create your own. The SF Symbols app lets you export a symbol as a template in a reusable, vector-based file format.

and also

When you export a symbol introduced in SF Symbols 2 as an SVG template and bundle it with your app, you can use it in apps that target iOS 13, Mac Catalyst 13, tvOS 13, or watchOS 6, but without the benefit of SF Symbol 2 features like multicolor support and automatic localization.

The mentioned SF Symbols Tools to export and verify SVG format SF symbols can be found here.
See how SF Symbols 1.1 app that
requires macOS 10.14.4 or later looks like.

The arrow.clockwise symbol is not marked with (i) which would tell you about copyrights and other informations that you would have to respect.

The exported SVG file contains all weighted symbols and layout guides to keep up this SF Symbol features and will help you develop graphics with it. The Format is explained here

This SVG file can’t be dropped as is into your Apps Assets unless you are targeting OSX 10.15 or iOS 13. The compiler will warn you if you try to do this below the mentioned versions. But you can open it in Sketch or similar to edit the SVG data and generate a graphic as workaround. Which i would suggest to do so and load this graphics into your UI Element instead.

The use of System Font Symbols starting iOS 13 and how to load them is explained here

and as you did set your UIBarButtonItem programmatically in code it could also be written like..

UIBarButtonItem *barBtn = nil;
if (@available(iOS 13.0, *)) {
    UITraitCollection *trait = [UITraitCollection currentTraitCollection];
    barBtn = [[UIBarButtonItem alloc] initWithImage:[UIImage systemImageNamed:@"arrow.clockwise" compatibleWithTraitCollection:trait] style:UIBarButtonItemStylePlain target:self action:@selector(refreshMethodHere)];
} else {
    barBtn = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemRefresh target:self action:@selector(refreshMethodHere)];
}