Endnote X8 - references missing fields

Hi Endnote community,

I am using Endnote X8.1 for Mac and I have a problem with some references that do not show any of the filelds (author, year, title etc.), but the pdf file attached is the correct one and can be opened. This occured after I updated to iOS High Sierra and sync.

Please, see screen shot. Any idea how to fix this annoying problem?

Thanks in advance,