I must be doing something wrong, but when I go to
`Refs -> New References -> Quick Add` and enter `https://www.jstor.org/stable/2975974`
it adds a blank reference with only DOI field automatically filled in:
Screen Shot 2022-02-20 at 23.04.20.png (14.19 KiB) Viewed 3238 times
Screen Shot 2022-02-20 at 23.04.33.png (28.06 KiB) Viewed 3238 times
I don't know, it works for me. If you go to that URL in your browser, do you see the article by Harry Markowitz? If not, you may lack privileges for it (although I wouldn't know why, since I don't have any special privileges).
Only the first and last of those should work, and they work for me (importing a reference by Bin Li).
But when I tried to fetch in from Crossref.org in my browser, nothing happened for about one minute and then I got an Internal Server Error.
So it seems Crossref's servers are having problems. I'd try again when they're back to normal. Note that they have periodic slowdowns, which they're aware of, and Bookends will time out if the response takes too long. That's what is no doubt happening in your case.