Scroll bar disappears after toggling full screen

Hello Vogelspotter,

Thank you for using Apple Support Communities. Based on your post, the scroll bar disappears often while using Safari on your Mac.

Does this happen with specific websites?

Try quitting the Safari app, then launching it while holding down the Shift key on your keyboard until the app opens completely then release Shift. This should remove the app's saved state and hopefully resolve this for you.

Should it persist, does this behavior continue while booted to safe mode: How to use safe mode on your Mac

Use sections, 'If the issue continues in safe mode' and 'If the issue doesn't continue in safe mode' depending on the results.

Hoping to hear back, take care.

Hey Vogelspotter,

Did you happen to restore from that Mac's backup when you set up the Mac mini originally? That could have transferred the issue to the new Mac.

In System Preferences > General > under Show scroll bars can you select on the other options 'Automatically based on mouse or trackpad' or 'When scrolling'? Does it show up and disappear, as expected? Then select back on 'Always' to re-enable the scroll bars to show all the time?

What happens if you try to reproduce the issue in another user on the Mac? Here are the steps to create another Administrator to test this: Set up users, guests, and groups on Mac

When you go to System Preferences > Displays > (you may need to right click to show display settings on the monitor here) what's the resolution reflect here? Is it scaled or set up as default for display? If you select 'default for display' does that scroll bar appear again normally when you test the issue in your normal user?

We'll get to the bottom of this together, cheers.

You're welcome, Vogelspotter.

Did you happen to test this further in another user on the Mac: Set up users, guests, and groups on Mac

This will really help us isolate the issue further. Testing in another user tells us if it's user specific or not.

Hoping to hear back, cheers.

Hey Vogelspotter,

Sorry for the missing that on our last reply. Does the display have any issues with overscan by chance? Learn more about that here: About overscan and underscan on your Mac, Apple TV, or other display

It sounds like this continues in other users and in safe mode. Which tells us it isn't specific to a user or third-party extensions.

It would be best for you to contact Apple from here: Get Support

Wishing you well, take care.