In current versions you do not have to enable it, before you had to add a deep analysis option.

What data type do you want to preview btw? And which version are you running?

What data type do you want to preview btw? All data type like doc xls pdf

And which version are you running? 11.24

If you successfully ran content indexing you should be able to preview these file types when browsing the project/data source within data governance section.

Go to Activate - Sensitive Data Governance - Click on your project - Click on the File System tab, assuming you used the file system as a data source - Click on Review - search the file you want to look at - click on the file and a preview should be generated, additionally with the entities you configured when setting up your data classification plan

P.s. Make sure you enabled “Index file content” on the data classification plan, otherwise only metadata is collected

@Jos Meijer I had already enabled "index file content" but it still doesn't preview files.

Consider that I am performing a discovery on the data online and not on the ones already protected.

@Jos Meijer  If the discovery I do it on the data already protected it works !!!

So I understand that on online and unprotected data the preview does not work.

Hi @Gabriele Palumbo 

That is correct, the data needs to be processed in order to collect the metadata and perform content indexing. Online data preview cannot be provided as this would need on-the-fly content indexing which is not available.