Customised Header suddenly not appearing

Hello,
I’m using the Isola theme for my blog https://themidnightstation.wordpress.com/ and my customised header has suddenly disappeared and stopped appearing. I have not changed anything about my browser, Google Chrome, or my header, but it not longer appears on my main page or on post pages. I’ve tried to remove cookies and cached images, I’m using a supported browser and I’ve tried to use a different browser to test it out, but nothing has helped. Does anyone know why my customised header may have disappeared and what I could do to fix this?
Thank you