Others have reported this happening on some mobile iOS devices. Unfortunately, I only have an Android device to test on. I do have some suspicion on what could be causing it which I try to fix on the next update. You could test the upcoming version found here. I’m hoping it fixes the issue.
Note: Since you’re using the logo option to fill the entire header you could add this on the Custom CSS option so that there’s no white space when viewed on smaller screens.