PDF-files change name and filetype when working with portfolio in Adobe Acrobat DC PRO FRL

Hi 

We're having trouble with our new version of Adobe Acrobat DC PRO FRL, since some of the PDF-files change  name, when the files are open as a portfolio. The name of the file changes around every 3 senconds, and it is random files every time. Not files with specific names. It changes back and forth to PDF, but when the file has .pdf + what looks like Chinese, it is not possible to acces the file. 

How can we fix this? Any suggestions? We would like to have the titles of the files to show properly in our own language - Danish.