Safari loads pages, but sometimes does not render (Is it 5k related?)
I have been chasing this problem for several months now, and am at my wits end! On my 2019 16" MacBook Pro (very fresh MacOS Sequoia install after full HD format...all extensions off..)
About 1 in 20 times, a page from any site I am navigating loads, but then is not fully functional. Sometimes that means that you scroll down the page, only to find the page stops prematurely, with no content below a certain point in the page. It's as though there is a horizontal line, above which there is content, below which there is none. Sometimes this cuts words or images in half, consistently across the whole window.
What's bizarre is that the page is fully loaded. You can view the HTML/JS/CSS source, and it's all there. You can even right-click on a blank spot below the line, choose Inspect Element, and be taken right to the HTML...it's there, but not shown on the screen. Sometimes, if this happens lower on a page where you've scrolled, when you scroll up, the top of the page is now blank/invisible too. (It was there before scrolling!) It's as though the rendering thread for the tab just quit.
Once a tab has this problem, it's toast. You can reload or navigate to no avail...the content doesn't visually update. But again, the current source is there, and you can "Inspect Element" for the elements of a page you now can't see at all. (You still see the old, incomplete content.) However, a new tab will function, on the same page even.
The only event that seems to coincide with the failure starting is my purchase of a 5k display, and in other threads in the Community, it seemed odd how many of those were users with 5K (iMacs, mostly). This could be a red herring, but I also noticed no failures when I was traveling, using only the built in display. The problem is intermittent, but would have fully expected to see a failure in the week I was not connected to the display. Maybe there is a memory management problem that occurs when the pixel count exceeds some threshold?
Is there any way to monitor the WebKit threads to allow me to dig deeper into my hypothesis?
Firefox/Chrome have no problems, and so I am begrudgingly moving towards adopting Firefox. (Yes, also using WebKit, but I don't think it is shared.)
Anyhow, any help or advice would be appreciated!
MacBook Pro (2017 – 2020)