A newly saved PDF name is not shown in the Read thumbnails.

I often have several PDF’s open in Adobe reader, so I use the thumbnails (list of files when I put the cursor on the Adobe Reader icon in my Windows taskbar) to locate a particular file. 

I’m not sure when this started but now the filename in the thumbnails doesn’t get updated to reflect the new PDF filename. Instead it remains the same as when the PDF was first opened in Reader. Is this a bug? I’ve looked for a way to refresh the filenames but have not found any. The only “solution” is to exit Reader and restart it (I have the option to reopen the PDF’s that were open in the previous session).