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.