This file is in use

Hi, I hope someone can help me. This has happened to me twice now.

I am using Office 365 desktop version and Endnote 20. When using CWYW, Endnote asks me for a library and when I try to open the library it complains that it is already in use. This first happened to me on a document I was editing (that I had originally made with X9) and I thought that maybe that was the problem so as a test I started a brand new file, added a couple of references to it and then tried to use the file with the new Word document. I still get the same error. I’ve tried closing everything and starting again but even with Endnote officially closed, it still happens. I have rebooted my machine. I don’t know what else to try.

Any help gratefully received,