save pdf to zotero from within preview fails

[chreman]

I have a zotero plugin for firefox, when I open an open access article in the pdf preview, and then click on download and select the 'save to zotero' button (in my plugin it is one of the download options that opens up after that), unfortunately it get the message "saving the link failed". going to the html version and manually saving the pdf from the link there works.

[chreman]

update: for some links, for others it works. will try to come up with a reproducible example.