safari won't full screen

Sorry, but that is just not enough information in order for us to be able to assist you with a potential solution.

Writing an effective Apple Support Communities question- Apple Support Communities

Try going to System Preferences/General and uncheck Close windows when quitting an app. Open Safari, use command - control - F to go full screen. Then quit Safari, reopen, and see if you get full screen. If that doesn't work, there is no way I know of to force it to open in the full screen mode.

I am experiencing the same thing.

waching a tube video like PBS Newshour, - when pressing the full screen icon, I get a message that my browser does not support full screen viewing!

watching a non tube video in Safari, the full view icon (button) is no longer there!

Conclusion is that Safari apparently no longer supports full screen view.

Any solutions?

You might want to consider starting a new discussion. Since this one is marked solved, less people are likely to look at it. A new post would be much more visible. You can link to this one.

I'm not familiar with an iPad Pro, but will Safari go to full screen if you aren't watching a video?

Did you try going to Safari/View/Enter Full Screen? Or use command - control - F?

Just to clarify, I am experiencing this on my iPad Pro, iOS 11.4

So far, at least, no problem with full screen on my MacBook Pro , OS 10.13.5