[WPMU DEV Dashboard] Updates WPMUD DEV

I am having some problems to update WPMUD DEV on soe websites.
I am getting this error “Update Failed: The update cannot be installed because we will be unable to copy some files. This is usually due to inconsistent file permissions.””
I did check the pemissions… We have 755 for folders and 644 for files.
Please We need to help with this.
Thank you!