Why do I get the message "security policy restricts clearing of this app's cache"?

[Drathic]

When I go to the storage tab under settings I clear my cache portion as I have always done. However when doing this on my wife's phone she receives the message "security policy restricts clearing of this app's cache" and still leave around 12MB of data under the cache portion. It is not a lot of space use, no, but I would really like to understand why this is happening. Thank in advance.

 

[N4Newbie]

Does she have a work email account on her device? Specifically, an Exchange server account?

Microsoft Exchange Server admins can set a number of security policies for mobile devices.