Let’s say I have a document where an image is linked to the hi-res image on my local. The links panel says the image is linked where I think it’s linked, and not in need of updating. But it looks crummy onscreen (high quality display) and, even worse, exports crummy as a PNG. If I then relink to the same image in the same location, it sharpens onscreen and exports a sharp PNG.
If I close the document and reopen it, the image is crummy again. This is happening consistently so that I have to relink every time I export, even if nothing has moved from where it was five minutes ago.