PDFs not saving to Zotero using "Save to Zotero extension"

Previously (up until last month), when I saved an article (from e.g. ScienceDirect) the PDF would automatically be saved and embedded into Zotero. Currently I receive an error with a red X saying "X ScienceDirect Full text PDF". I've reinstalled both Zotero and the Zotero add-in for chrome. But the problem persists. Has anyone experienced a similar issue, if so what solutions exist?
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