First thing to check is if you’ve correctly chosen tokens to be shown on the widget:
Android – click the gear icon in the upper right corner of the widget and then you’ll see list of tokens to choose from. Toggle those, you want to be shown on widget.
iOS – tap the widget and hold until a popup appears. Click “Edit widget” and then you’ll see list of tokens to choose from. Toggle those, you want to be shown on widget.

On iOS if you still cannot see the codes, even if they are added in the app – you need to open the 2FAS app, go to Settings and turn on (toggle) the widgets option.

On Android, if you can see the names of services in the widget but can’t see the codes, it’s alright, that’s how it’s supposed to work – tap on the name of the service, and you will see the code.

Remember to have the codes activated in the application before adding the widget. Otherwise, you will not see any codes. Additionally, remember to run the application at least once before enabling the widget.

Widgets, on both operating systems, are independent extensions of the application, and sometimes the codes may not load immediately after turning on the phone. If that happens, wait a moment, run the 2FAS application, and the codes should appear.

If none of the above works – restart your phone.