I have many different bases which will have a table that has attachments, and then linked records to other tables within the base which then lookup the original attachments. As of yesterday and all days prior, I could open the attachment in the lookup field in the linked table directly. As of today, I can still see the preview for the attachment being looked up, but when clicking on it the cell goes blank and it won't open. My attachments are mostly PDFs but I'm seeing the same "won't load a looked up attachment" in other bases with photos and word docs as the attachment as well.
Looks like it is an issue in the web interface and desktop app, possibly not in the mobile app (android) though.