EndNote PDF view error

Hello everyone, 

I am wondering if anyone can help me to figure out what is happening with the PDF viewer of EndNote. 

I use EndNote 20.1 which suposed to allow me viewing the PDFs on the same window. However, for some reasons, the attached files are not detected by the EndNote, and as a result, I am unable to view pdfs on the same screen which is very inconvenient. I have created a new library, attached all the PDF articles again, but the error keeps ocrring and tells me that the references are “unfiled”. 

I have attached a screenshot that can help you understanding what it looks like in my case. Please have look and any help is appreciated! 



I have exactly the same problem and I don’t know what to do. I can see in the ‘Summary’ tab that the pdf is there, and I can open it with Acrobat from Endnote, but the message in the ‘PDF’ viewer tab says ‘No PDFs attached to this reference’. 

Sorry I can’t help you, but maybe someone can assist?