I am using Zotero 7.0.20 on the Mac, and am having a weird issue where it stops finding metadata for uploads. It works for 3 or 4 PDFs when I drag them in, then it just stops working. The Metadata Retrieval window just shows Processing and never completes. I've tried with multiple PDFs so a particular PDF is not the issue. If I try to manually retrieve the metadata, by right-clicking and choosing it from the menu, then nothing happens. If I restart the program, it still doesn't work. If I restart my computer, it will work for 3 or 4 again, then stop retrieving the metadata. Any thoughts on how to fix this?