After firmware upgrade 2.31.195 for My Cloud EX2 Ultra: I can't use the app Viewing file for any user

Hello to everybody.
I need your precious help.
After upgrading the firmware to 2.31.195, the Viewing file app button, (functionality that I configured for all my users), doesn’t appear after the login both for admin user and non-admin users.
So, my users can’t have the features of upload and download files and creating directories on their space.
How can I solve this issue? Is it a bug of the new FW version or is it possible to find a workaround for this?
Thank you in advance.

If you mean the Webfile viewer feature, please read this article -

Ah great ! Thank you Jchen.
I understand: it was a security issue. Previous firmware installed in my WD MyCloud Ex2 Ultra gave this feature to all the users.
I think that I can also resolve the access by mapping network drive \mycloudex2ultra\userfolder using admin privileges ( the admin user in WD Mycloud EX2 Ultra).
The problem is that my WD MycloudEx2 is in a Lan with Active directory and domain. So, I need to test if this works.
Thank you