I'm using Word 2019 on Windows 10, and have recently ran into a problem.

When I get past a certain page length in Print Layout (or perhaps word counts, not sure how it's calculate), the screen will blink once, then went back to normal (henceforth referred to as the Flashpoint). Everything still work as it should, but for some reason, the cursor (the blinking vertical line to indicate where you're typing) will start acting weird. Here's how:

1. If I start typing, moving it with an arrow, highlighting, whatever that makes the cursor move away from the original position, it turned invisible. Functionally, nothing is amiss, I just can't see where it is
2. If I use the mouse to click to any random spot, the cursor will appear again, and stay visible until I move it around as stated above.
3. Moving up past the Flashpoint will also make the cursor visible again, and I can move it around like normal without it disappearing (as long as I don't go down past Flashpoint).
4. If I zoom out, the Flashpoint is seemingly pushed further downward. The cursor will be visible and act like normal for many more page, but if I go down past a certain point, it's Flashpoint Paradox all over again. If I zoom out further, the Flashpoint is again pushed downward.
5. If I switch to draft view, the problem went away completely. No more Flashpoint, no more disappearing cursor.
6. This is NOT document-specific. Any new document that's long enough (regardless of template) will run into the same issue.

So far I've tried rebooting, copy the content to a new document (no formatting), convert document to .doc file, turned off and on Use Smart Cursor, and nothing work.

Is there any way to fix this?

How big a document?
We do not need the lower limit, just some point at which you are seeing this happen so we can try to reproduce it.

At 130% zoom, the flash start when I scroll to somewhere in the middle of page 283. The document is 995 pages in total.

Note: this seem to be related to scrolling only. If the viewport (I don't know what the proper term is) don't scroll past the middle of page 283, I can move the cursor and see it like normal. If the viewport moves past that, even when I place the cursor at a line it previously could stay visible when move, it still disappear.