Random Users cannot save documents to root of their personal folders. They had no issues for years saving to a mapped personal drive on the windows 2012 R2 NAS server, U:\. However, they can save to a subfolder under that U:\ root.
Permissions all look correct; user has modify permissions.
Any advice would be greatly appreciated.
If it's random users and not everyone, I would start looking to see what group those who can access their U: drive and those who cant.