cannot click on "Clear Data" in the Application Manager

I use galaxy s3 Neo, not rooted device.

I noticed (in Application manager) that there are some apps that can only be stopped.

So when you select the app, the only thing you can do is "force stop", the other options cannot be selected ("uninstall", "clear data"..).

I understand that maybe uninstall cannot be made for some reasons (talking about system apps), but why "clear app data" cannot be selected?

Even when I stop the app, I cannot select "clear data". Why is like this?

Then how I will clear the data for this apps?
Is there another way to clear the app data?

Thanks
Cheers

Can you give a few examples of what apps are like that?

Yes, sure.
CloudAgent, EpsonPrintService, FactoryMode... are the first that i've seen now doing one fast search... there are more 100%

Pretty sure non of those have data to be wiped. They don't store any.

Well CloudAgent does... I can "clear cash" but I cannot "clear data".... and there is some small data stored...
I am just wondering why it is like this?