Problems with saving images to your iPhone or iPad can occur when the app is used on a device for the first time. When the Apple prompt appears, asking if you allow images, press OK.
The Image is saved to iOS’s Photo stream.
For first time use, the image needs to be saved TWICE. Once set up, it should work fine.
If you have disabled images:
iOS 11: Settings > Logo 7 app > Allow Photos
iOS 12: Settings > Screen Time > Content and Privacy Restrictions
Further problems, please try clearing the app from memory or restarting your iOS device.