Which product are you using?
PDF.js Express Viewer
PDF.js Express Version
Detailed description of issue
Ask if full screen support is available on mobile.
It has been confirmed whether the full screen is supported on the PC, but the full screen support on the mobile version is not supported on the mobile version.
In March last year, I saw a forum post that iOS mobile devices do not support full screen yet.
I would like to know if the current viewer supports full screen in mobile version (Android, iOS).
Full-screen functionality on mobile devices (Android, iOS) works fine
Does your issue happen with every document, or just one?